Anybody care to discuss HP?/Torque?
I want to buy the engine pieces with purpose but I keep wondering what the purpose is. I want a strong motor that'll last. I think lots of power in the low to mid RPM is the way to go. So how much is too much? As MG's go how much do I really need? Maybe there's no such thing as too much. I read about converstions with 250HP up to 400HP. Does the guy with 250HP always end up wanting the 400HP? I think the problem is that I don't have a good handle on what various HP's 'feel' like in the B. I do remember driving Ted Laythrop's TR6 in Terre Haute. I would be very satisfied with that kind of performance. I'm not a race car driver. I'm a weekend cruiser with the occational need to be pinnned to my seat. So how does one put all the puzzle pieces together to make predictable performance? I'm lost here.
Torque is proportional to engine size. HP is where the camshaft makes peak torque. Want more torque? Get a bigger engine.
I tend to lug my engines, so I prefer a low RPM tuning. For me, that means a roller cam engine is a better choice. Although I'm building up an Olds 215 (3.5), if I were starting over, I'd go with a Ford 5.0 roller cam engine, install aluminum heads to save weight, and stroke it to 327/331 ci.
In the first post you mentioned Ted's TR6, which has a Chevy 350. I've driven it too, and agree it's a wonderful car. But I don't aspire to possess that sort of power. A smaller engine can be a lot of fun if it always feels willing when you mash the throttle. Toward that end, I don't think horsepower or torque tell the whole story. A short stroke. A lightweight flywheel. The right throttle return spring and throttle linkage. Setting up the carb's accelerator pump (or EFI) properly. Gearing. There seem to be an awful lot of subtle variables... Of cars I've test driven, Jim Stuart's burgandy roadster especially impressed me with its basically stock Rover 4.0 and EFI. It was a revelation to me because it's so very smooth, quiet, and composed. Great throttle response. No bog ever. Easy to drive well. That's finesse! Another liter or two might be nice, but there are some very satisfying cars on this website that have a lot less than 250hp.
Thanks for the responses. A few others sent me private E-mails with motor specs of their own. Thanks to you guys, too. It's all helping me understand what I'm trying to do here and your perspectives are just what I need.
Paul,
I have the 5.0 roller tappet motor as my starting point. Have you driven a stroker 302? Is that how you know that's what you would do given the chance? What was appealing about it? As far as strokers go, other than more displacement and hopefully more engine performance...would the car feel different? In other words can you tell in 'streetablility' when a crank has been stroked?
Hi Curtis,
I really appreciate your perspective. So there is such a thing as too much...
You mention 'short stroke', just to keep things from getting to big? or are there other disadvantages to a stroker?
Can you tell me more about the 'bog'? Is that inherent with big displacement small blocks or are they just harder to time?
With regard to:
--some very satisfying cars on this website that have a lot less than 250hp--
I'm happy you said that. And to tell the truth, after I posted the initial thread I regretted it. While I am interested in how all the 'subtle' parts come together from a mathematical and practical perspective, I don't think it needs to take away from the fun of doing a project like this. Then I remembered how much fun I had in the B before I took it apart. What was it like 110HP, max? I used to zip around and have a ball. Even with the stock 302 setup and some consciencious weight adjustments I'm ahead of where I was, right? So thanks.
I'm back on the planet again. Still curious, but not concerned.:)
Brian, my 302 has just settled in between the fenders and I can only speculate as how it will perform but I chose to go with a stock 302. I've owned the car for thirty years and for most of that time it has been my daily driver. I have a Ford truck that gets from 7 to 14 mpg depending on how it is loaded and a T-Bucket Roadster that will scare you to death but doesn't do that well when you put your foot in it. I need something that can return a little excitement to my life that doesn't cost my entire pay check to drive. Of course, when the need arises I can take the Bucket around the block, but for me, the car has got to be street-able, not to say big horsepower isn't, but I went with what met my needs.
"P"
I think some perspective from the big horsepower crowd is in order as well. It's not necessary to have an evil handling or unstreetable car as your power levels go up. In terms of tuning and response, what works well for a small V8 also works equally well for a larger one. It's not necessarily the displacement that determines how tunable or responsive the engine is.
Of course it's easily possible to build an engine that is not well suited to street use, people do it all the time. But the opposite is equally true and the secret is in the right combination of parts as Curtis said.
So I will say this. There's almost a magical line you cross with an MGB when you get into the 300 HP territory. The car will handle that level of power well and it will do things not formerly possible. It will demand a different driving style as well, and will insist that you mind the throttle. One of our group posted a track video not long ago of his car which is in this range and watching closely you can tell that the car just itches to get loose coming out of the corners. For someone who has driven such a car, just watching that video gets the adrenaline going, and I will say this about horsepower, it is highly addictive. You can increase it, but it's very difficult to willingly go back.
JB
Not being a wordsmith Jim, I didn't explaine myself well, sorry. I drive a rather big horsepower 1800 lbs car also and wouldn't take for it; I find I need an occasional adrenaline fix too. My intent was to suggest he build the car to fit what he wants it to do, I just didn't say it very well.
"P"
Brian, I haven't (yet) stroked a 5.0, but I do drive an 86 5.0 HO. Yesterday I got 26 mpg on a 300 mile trip. When I got home and saw the soft tires I kicked myself because I could have gotten an easy 27 or more.
I would go with a stroked 5.0 because it's the easy way to get more cubes in a small engine block. Also, the extra stroke gives the engine a more low-end torquey feel, and that fits with the way I drive.
No problem Paul, my comments weren't directed at anyone in particular. From what Brian has said it sort of sounded like he'd be pleased with a motor that has a good bottom end. So far as I know there's no better way to get that than more displacement. (A blower would be a close second though.) And so far there's no better example of the "Too much is just right" approach than the MGB-Roadmaster with it's 455 Buick engine running mild compression and a very streetable tune. Only a few of us have driven it up to now and only for short distances but it definitely has the bottom end covered. Is it too much? So far nobody thinks so.
So I think the question of how much horsepower is too much is best answered by looking at the state of tune of the engine. 250-300 hp in a 215/3.5L is likely to be too much for the street in the minds of at least a few drivers, whereas 500 hp in the MGB-Roadmaster or in my blown 340 is not. It's a pretty relative question.
Jim
Yes indeed, it is all realtive.
There are Camaros and GTO's running around town with welll over 1000 hp and driven on the street. You can only drive at or a bit over the speed limit. So the 1000 hp is good for ???? show and tell, unless is those ponies are at the track.
It is nice to say" I have 1000 hp" great or I have a 572 ci now when are you really going to use it.
I have well over 550 hp in on of my cars. Very rare can I really open up the Throtle body to feel the ponies doing its thing.
and that is in the desert and praying that I do not get the car impounded.
Nothing wrong with lots of power, it is never enough I am all for it. But I am a bit practical, even in this hobby there is some logic to what we do. As an exercise to see what if...etc great, why not
If somone has 1000 hp and keep those pomies in a harness and that is what they want THUMBS UP TO YOU !!!
There is always a good conversation on how it was done and many of us can learn from it.
Most of all it is fun building something that has been done,but different. I suppose that is the real reason.
Brian, a lot of the feel of a car is determined by the gearing and engine torque and it doesn't have to be extremely high to feel that rush and be pushed back in the seat. You get good torque coming in low in the rpm range and a medium rear gear aroung the 3.4 range and you'll feel that rush when you mash the throttle in first or second gear. My little 2.8 Midget with all of 120 screaming hp will definitely push you back a good bit, just have to keep the weight down and the gears right and I still get around 25 to 27 mpg on the road. That said, I can't wait for a chance to drive the Roadmaster and feel all that torque. It's been years since I drove a big block car, nothing like them for sheer lower end power.
Yes, there is always a rush when big hp comes in to paly, correction, when the torque starts to work.
Regardless of size. I agree with Bill Y.
As Jim put it, it all depends on the choice of parts and combination. With the new electronics 900 lb of torque in the street is like a pussy cat. Both, the big V8 and V6 will drive at the same hwy speeds.
Of course, we all enjoy a mild "exhibition of speed" every now and then, if it's nothing more than rolling away from a stop and then just barely breaking the tires loose. If you drive in the hills, even more so, since there you have ample opportunity to use all of that torque passing on 2 lanes uphill and running the twisties. But don't get me wrong, Bill G has a valid point. Somewhere along the line enough is enough. For some (You Bill? ;-) ) it may be a V6 or even a 4. For others it may be when full throttle at 70 mph breaks the rear tires loose, and even that may not be enough for some. The beauty of living in this country is that we don't all have to have the same thing.
JB
Yeap, enough would mean a 572 ci V6
Bill, I think you mean the 478 ci GMC truck V6 from the mid sixties! LOL Now that would get you some torque. Seems that talk about a similar V12 version of that engine was the start of some brainstorming that led to Project Roadmaster if I remember correctly. http://en.wikipedia.org/wiki/GMC_V6_engine
478v6-5.jpg
Brian wrote:
QuoteSo there is such a thing as too much...
You mention 'short stroke', just to keep things from getting to big? or are there other disadvantages to a stroker?
Can you tell me more about the 'bog'? Is that inherent with big displacement small blocks or are they just harder to time?
For the record, I didn't actually say there's such a thing as too much. In specific reference to the Chevy 350, I said "I don't aspire to possess that sort of power." I understand why other people want a lot more. There are pro's and con's to each of the popular engine choices.
Why did I mention stroke length? There are in fact a couple advantages to a shorter stroke, but first and foremost is inertia. Unless you go to significant expense and/or effort, it's very difficult to increase stroke length without also increasing rotating mass, so in essence you get similar result as if you used a heavier flywheel. (The engine doesn't want to rev up as quickly when you mash the pedal, or slow down as quickly either. It makes the car feel less sporty.)
Historically, most British engine design had long strokes and small diameter pistons. In the early sixties, British Ford introduced a short stroke / big piston four cylinder engine. In any racing class where people had a choice, BMC (MG's parent company) popularity immediately dropped. Companies like Elva, Turner, Ginetta and others switched from BMC engines to Ford engines. Ford gradually became the main supplier to open-wheel classes too. However, I believe Ford's success was because they exploited a second advantage of a short stroke / big piston design: it gave them room to package bigger valves and better flowing ports, and the result was better combustion.
With regard to 'bog', I think I was mainly thinking of the difference between a large throttle butterfly and a small one. A carburetor (or EFI system) should be sized appropriately for the engine and the engine's use. Very often, a modestly sized carb actually makes a car feel snappier in traffic. That's not really anything to do with big displacement engine vs. small - I was only reinforcing the point that there's more to the story than torque and horsepower.
Curtis wrote:
"Historically, most British engine design had long strokes and small diameter pistons."
Funny thing is this had little to do with engineering and more to do with the British road tax structure which was determined by multiplying piston diameter by the number of cylinders. So a small piston/ long stroke motor would be taxed less than a large piston/short stroke motor of the same capacity.
Regarding the HP/torque discussion, I've always thought too much torque in a lightweight British roadster can be a liability. Torque is that twist that helps launch a car off the line, in other words, "tire fryin' power". In order to effectively use that torque it has to get to the ground, which usually means big tires and tubbed-out wheel wells. I've been wondering how the Roadmaster is going to control the torque that big Olds is going to put out. Should be interesting!
QuoteTorque is that twist that helps launch a car off the line, in other words, "tire fryin' power"
That's just one aspect of it. Torque is also the twist that helps you get from 45 to 70 in the passing lane. You don't have to be a drag racer to appreciate/enjoy gobs of torque.
It's Buick engine Rick.
JB
Doh!!!! Sorry, Jim, don't know what I was thinking. I'm still interested in the torque factor in the Roadmaster. I have a Chrysler SRT-8 with 425/400 hp/tq. Even in a heavy car like that and traction control I have to be careful, particularly in the wet. I imagine you'd have to be a bit more careful in the MG.
Bill, the 478 ci was actually stroke to 572 ci and it was use on a baja truck in the early 70's
Brian C.,
You remember those cars that came as part of the 1970's? The ones that were jacked up in the rear because it was cool or whatever? The majority of people did that because they understood that it made the car fast for cheap. If was what they did for wide rubber under a body designed to take smaller, the motors were sometimes given power but I think many people ignored the parts between. The designs were poor.
Now lets go to an MGB that was originally designed with much lower BHP/Tq- you want the power to hook up- NO Question!
You are not going to jack the car up, well, if you do its no longer a sports car, its err, a drag queen? How many MG owners purchase their cars to look like a 1970's American car? None. For drivability AND appearance, we keep the cars low on all four corners- but this also limits us as to how much power we can put to the ground.
What do we do to get the power to the ground? Maybe flare the rear, maybe tub- both Really costly (out of half of our budgets) We use the best rubber we can find, place limited slip in the rear axle and maybe naroow an axle so we can get that 215 in the rear instead of that 205 series. All of this costs money but in the end, we get something that sticks.
Suspension in the rear become very critical when you no longer have a car that just needs to handle well in the corners but on take-off. Now you need to spend a bit more in order to make the product work properly. Too much BHP/Tq is not going to do anything but wear out your rubber shoes but if all you want is a cheap way to burn rubber...
Another thing we do is look at weight reduction, gearing of the rear axle AND gearbox combo (improper anywhere slows you down)
MGs and other small British cars were never designed to hold the BHP that we place in them. If your going to build a 600 BHP with about as much torque out of a SBC or SBF, leave the rear end stock, leave perfectly stock wheels and tyres, leave the stock rear suspension, leave the stock front suspension, leave everything else on the car set up for less than 100 BHP, I can assure you a V6 MGB with a decent suspension, axle and tire setup is going to beat you to 60 MPH. Sure after 60 you can beat that car to 90, but I would ask whether your car is safe at that point.
Now there is not formula that I am aware of but I would suspect that adding 50BHP more to a car is relatively safe with an otherwise stock car.
Adding 100BHP/Tq to a car and you need to start looking at tires and a little in suspension if your planning on getting on the car a bit.
Adding 150 BHP/Tq- your going to start getting a bit more serious about building the rest of the car.
So on and so forth.
Now I am not saying you need the latest and greatest, but often we tend to go in that direct.
So how much is too much? Depends on the job your car is built for. Even with 2,000 BHP/Tq in your otherwise stock MGB, dont expect to kill Vipers or AWD 911 Turbos- you will find your dreams literally go up in smoke- rubber smoke!
Myself- for Bragging rights alone I would like 200 RWBHP. With my stock 3.4L untouched it has 140 BHP/ 185 Lbs Tq at the rear wheels. I am in no rush to get there- I need to install my 3.42 limited slip rear axle and other items first.
-BMC.
Great job, Brian.
Just for the record, I'll be the one that goes out there & declares that there is such a thing as too much torque/horsepower...................... I just haven't experienced it, yet. ; D
Seriously, remember MGBs were/are meant to be sports cars, not Funny Cars.
300-350HP, 300 or so lbft seems just about right for a well sorted MGB. I don't know how well I'd do in a drag race vs a lower torque conversion, but since I'm not into drag racing. it doesn't really matter (although I think I'd win in the quarter, probably even in 0-60 - traction is NOT a problem). It does every thing I want it to do, and does it very well indeed. Handles well, stops well, and kicks me in the back hard when I get on it. Looks pretty good too, more like a sports car than a hot rod.
As far as I'm concerned, a 300HP Ford 302 MGB is just about perfect.
Dan,
I make it a point to never argue with perfect. ;)
That said, I do believe that those with stock MGs would be ecstatic with 200 ft/llbs of torque & 160-200 rear wheel horsepower.
I think so too Carl.
I have long said that for the *average* driver the 60 degree V6 is the perfect compliment to the MGB. It's just the right size, both physically and in terms of power and has some room for upgrades. It transforms the car and is very driveable. OTOH, the BOPR has the ligitimacy of a factory build for those to whom such things matter, and they appear to be in the majority since that swap still remains the most popular one. Upgrades from there are numerous and powerful, ranging clear up through the Buick 340 with a 5.7 L build being fairly simple to do. The SBF swap has proven itself and a less expensive route to power has not been discovered. This makes a very fine car. And finally at the upper end we have cars like the MGB-Roadmaster 455 Buick, the LS series swap that Pete is working on, my blown SBB 340 and a few others, very tractable and feasible conversions but largely untested and unproven. In the next year or so we should be seeing just how well the car holds up to these power levels, as well as how some alternative rear suspensions perform.
I agree with Dan M that 300hp is a very good power level for the MGB. Spend just a little time with one and it will make a believer out of you. Formerly I felt that 240hp was really all you could want, but I was wrong. Before that I felt that 200hp would just make an exceptional car. And I was right. As does 140hp. So my point is that with this car any substantial increase, say of 50 or more additional horsepower, is going to simply cause you to be ecstatic about the improved performance of the car. So in that sense *every* swap will be the right one. But it's a good idea to look to the future because as good as the new power level is (and it will be very good indeed) there is still more to be had if you want it. You can satisfy yourself at any point and say that the suspension or the tires (or the driver) might not handle the extra power and that could be true. But we continue to prove that it ain't necessarily so. And as much as I do appreciate Carl's dominance of the autocross course with his truly magnificent driving skills, out on the mountain roads, horsepower rules. (well, that and huevos)
Jim
Quit embarrassing me, Jim. There are quite few drivers in our group. My car is just set up better than theirs. ;)
"out on the mountain roads, horsepower rules"
Probably not so much on roads like the Tail of the Dragon.
cojones.
cojones.
The key to driving those roads.
Amazing Jim and Dan. Using a word that actually comes from Galicia Spain. It is galician dialect.
I said 300 only because I've never driven one with 400. It may be that 400 is the "just right" number?
Carl, who was in front last time we were on the Dragon?
JB
I was until I pulled over & let someone else lead. ;)
Wrong !!!!! I am going for the max 347 ci 500 hpVortech Supercharger, going for 7-9 psi good for an extra 150-200 plus (street boost)---700 hp NOW what it really counts 650 + lb of torque rear wheel numbers. Oh yes some juice good for another 100+ hp. do not want to go overboard.
This package will be control by an ECU with 1000 cfm throtle body.
I should be able to crusie the streets at speed limit, enter the FWY like everyone else, ok! just a bit faster, drive at over the speed limit by 10-15 mph, I will be able pass anyone when I have to, except a police car.
Then I can drive the car to the local road course for track days and dirve it a half throtle or less.
When I park the B in the garage, I will figure a way to get more power from it, it is never enough. LOL Just having fun guys.
On a serious note. There is no magical number to say it is enough, not sir. Enough is when you have reach the limit of the engine you have or satisfied as Mr. Masters. Now if we take Mr. Masters GT and.....nooo it is just right as it is.
The magical number could be 200 or 900 +
I've been observing from the distance. This is exactly what I was hoping for. Thanks for chiming in everybody. I've gotten a 'sense' of what I'm looking to accomplish. Honestly, I think the 300hp/tq range sounds about right. As I mentioned earlier, I'm using Ted's front end, he also set me up with a Ford 8" off a Grenada (I think). It has 3:27 gears with an Auburn positraction and the Willwood disc brakes. I'll use the T-5 transmission. For the rear suspension I've read some about the 3-link setup, though I'm using the 1" lowering springs, tube shocks and sway bar. The only issue I have'nt ironed out is the rear wheels/tires. I'd love to put a little flare on there, for looks, but also to get enough rubber on the car. Unless I mail the car to somebody the only way to get flares is to do it myself. I've got some decent welding experience over the past 5 yrs, but maybe the welding is the least of my worries on a project like that...
Anyway, from all the banter on this thread, I think the 300 range, with the drivetrain setup, sounds like a nice fit. Any comments welcome. Thanks again, guys.
what does 200hp feel like? I know what 150hp mgc feels like Maybe I need 300 to enjoy
Have quite a bit tied up in 215 conversion stuff. Wanted 100hp nitrous shot on 215 olds to make that 300. Cost big bucks for forged pistons though. Any ideas what it would cost to build 300 hp rover block vs 215 olds
Until recently there was a tuner car shop a block from our hanger/shop/hangout. Though none were what I would refer to as World Class Tuners, they were amazed at the performance of a Bucket and, as a general rule, only tried their luck once. I would always tell them Horsepower is great, but its torque that makes the world go around and if you doubt that go drive a big block. Buckets, no matter how well engineered run out of down force and aerodynamics about three feet off the line and past 100 miles an hour or so become rather intimidating so given enough distance some would catch us and blow our door off (we only have one door on the passenger side you know) but being about half their weight doesn't hurt and that's something LBC's have going for them. "P"
PS: Any contest of speed was done at the airport. Understanding the need for getting from one red light to another and how precious our time really is, we don't condone or support street racing.
Hi Brian,
The arguement over hp and torque has been going on forever. It all boils down to the car and how it feels. Torque is what gets you moving and what you percieve. Horsepower is what gets you the high speed rush. In a lighter car torque becomes less of an issue due to traction and weight differences. Idealy you would want just enough torque to keep your tires planted and enough, horse power to mph where you want. But life ain't that simple. In my shop we sit down with the customer and spend a considerable amount of time to determine what they expect out of the car. Almost every time we build a less agressive car. The big burly v8 is attractive but isn't as fun as you would think. In our (British etc. ) cars it is too heavy. It destroys any sembelance of handling, and causes severe suspension and frame problems. Good choices seem to favour the higher rpm japanese v8s or the cadillac northstars et al. My own car is a stretched B with a 4 turboed 6.0L jag v 12. It's retardedly fast in a straight line (11.12 @127mph) but it won't out corner a pu truck. What do you want your car to do?
Cheers
Fred
"The big burly v8 is attractive but isn't as fun as you would think. In our (British etc. ) cars it is too heavy. It destroys any sembelance of handling, and causes severe suspension and frame problems."
That's an intersting statement. It's also untrue.
Fred wrote:
QuoteMy own car is a stretched B with a 4 turboed 6.0L jag v 12...
We need to see lots of pictures of this one!
(click here for How-It-Was-Done form and photo submission tips) (http://www.britishv8.org/British-V8-How-To-Contribute.htm)
I've had 3 different versions of a SBF in my car, 200hp, 300hp, and now 400hp/378lbs with the 331 stroker. I have no special suspension or brake upgrades, in fact I'd call it a ratrod compared to 99% of you guys! Except Carl of course. The car seems to handle it just fine and the torque is great, but I think 300hp is a good number to shoot for, especially if getting decent fuel mileage is a concern.
I like torque more than power in a V8. I have the usual Ford V8 (maybe 280 ft/lbs at the wheels and a fairly flat curve). It is fun to get strong acceleration from 1500 rpm in any gear and I do enjoy running it up to 6,000 rpm - the power peak is at about 5,800 rpm. Starting from rest in third is easy as well. I have been considering stroking the engiune to 331, the only advantage being even stronger acceleration in the higher gears, especially 5th. But in terms of starting fron rest and accelerating through the gears, the limitation now is traction, so a 331 would not improve things (except possibly on a drag strip with a stickier surface). But it would improve real world acceleration for times when I am too lazy to down shift. That brings up the interesting concept of using a modern 5 or 6 speed automatic with the "300 hp engine". Such a transmission has many gear ratios to choose from and down shifts every time. The instantly available torque multiplication from a lower gear ratio (or two) would go a long way towards filling the gap between a 300 hp engine and 400 hp engine by keeping the torque at the wheels near the traction limit more of the time with the smaller engine. This would be especially true with a "300 hp engine" like mine with a relatively flat torque curve between 2000 and 6000 rpm.
Larry, Good post. That is what I plan to do with the AW4 Jeep tranny(A340 Toyota)but mine is only 4 speeds, manual solenoid shift,OD 4th,narrower than GM. Jim Blackwood's is a bit wilder, with the 8 speed Lexus tranny. I plan on 300-400 HP which I think will be just right. Jim Blackwood is being pretty conservative in his 300+ HP estimate. I think the dyno numbers will be more like 450+ and give the Roadmaster a run for the money.
When are one of you going to make an AWD MGB V8 similar to Stuart's Midget?
http://gallery.brit-cars.com/showphoto.php/photo/6198/ppuser/447
Trevor, I wouldn't count on it anytime soon, Sierra 4WD units are a bit scarce on this side of the pond and I haven't run across anything else that looks like it would fit a Spridget. (Yes, I've looked, the temptation was just too great after seeing Stuart's car)
Until Stuart submits a How It Was Done article, I'm not sure I believe his Midget even exists.
AWD has advantages... but certainly not for every car and application. You might for example recall that some constructors worked quite hard to put AWD on Formula One cars, and it was an extremely costly mistake. What would it really do for a MG except add a lot of cost, complexity, weight (much of it unsprung), and rotating mass?
Here in Colorado, when I explore unfamiliar mountain roads it's not uncommon to have a twisty and smooth paved road suddenly turn into a gravel road. AWD might be nice on those occasions...
"Here in Colorado, when I explore unfamiliar mountain roads it's not uncommon to have a twisty and smooth paved road suddenly turn into a gravel road. AWD might be nice on those occasions..."
I sure know what you mean about those roads out there. I took a trip one weekend around Beulah and somehow wound up in the San Isabel National Forest. On the other side of the mountain was 16in of snow and ice on a dirt road. I was sure glad I had my superduty and 4wd then. Best road trip I ever had. If I get another job out that way I might buy a house out there. Colorado is the most beautiful place in the world in my opinion.
This is a wonderful thread. I have two questions.
1. At 300hp and beyond, and assuming a rust-free shell, wouldn't shell reinforcement become part of the equation?
2. With 300hp as a target, what would you suggest should be specified in a reman 302 engine without aluminum heads initially?
1978 MGB, chrome bumper conversion,rolling painted shell (Merc Brilliant Silver)
The MGB body shell is generally considered to be satisfactory at the 300 hp level, especially the chrome bumper models. On rubber bumper models it can be considered worthwhile to add a reinforcemet from the foward spring hangers to the cross member just foward of it. Some also add reinforcement on the left side to compensate for the absence of a battery box there (chrome bumper cars have two battery boxes, rubber bumper cars just one box). It is also wise to consider the effect of body modificatons such as plastic fenders and excessively large holes for through the fender headers. But I am sure others have different opinions on this subject.
It is always best to use a roller cam 302 block as the roller cams offer more performance at low modification levels than flat tappet cams. Essentially, roller cams generaly open and close the valves faster so there is more time at higher lifts without excessive overlap and duration. It is also a good idea to go with through the fender headers from the start as the freer flow makes higher power outputs easier.With these factors taken into account, any stock block Ford 302 will be able to make 300 hp at the flywheel with just a head upgrade (even keeping the stock cam). Heads are the main limitation on a Ford 302 in that the flow is limited, especially at high lifts. Thus, adding a high lift cam or high ratio rockers gives little benefit with stock heads. But with aftermarket heads that show flow increases up to 0.6 inch lift (or even more) cam upgrades can make a big difference. But stock cams in Mustangs are not bad, and with high lift rockers (1.7 ratio) and aluminum heads can give over 350 hp at the flywheel. If you want to upgarde the cam now, before adding aluminum heads, be aware that the stock valve springs cannot tolerate high lifts and it is probably best to wait untl aluminum heads are added to consider a cam upgrade. With all stock heads and most aftermarket heads, exhaust flow suffers in comparison to intake flow. Also, the header situation in MGBs hurts exhaust flow, so I prefer dual pattern cams that have more exhaust duration than intake duration. Kelly Stevenson has such a cam (a Comp Cams XE 266 HR) and he had the highest output of any 302 at the dyo session last year.
For induction, hood clearance is limiting. All that can fit without a scoop is an Edlebrock performer (not a performer RPM). This will still easily support 350 hp at the flywheel (with the right heads) but there is no use planning on using a high rpm cam or overly large carburetor with it. Therefore, this manifold with a 575 to 625 cfm vac seconbdary carb will be satisfactory for both an iron head 302 and an upgraded aluminum head 302 with just some jetting changes. You can also use the Ford fuel injection system (most likely with hood modifications) like Kelly used and this will work with both the stock and improved engine. That is, the later injection systems (with mass flow?) can be used on most modified engines without retuning, but the earlier systems are not so adaptable.
As a disclamer, my experience with engine tuning is limited and you might want to get further advice.
RE: For induction, hood clearance is limiting. All that can fit without a scoop is an Edlebrock performer (not a performer RPM).
Larry knows way more than me but the above depends on where you put the motor. I'm using the fastcars IFS with ford mounts -- sets the motor back (far enough that clipping the corners of the firewall by the heater shelf is required) & low. I'm waiting on my 1 1/2" drop base to arrive but if my measurements are right using a 2" filter it'll clear the stock hood with no bulge and my Performer RPM air gap (clone). Base should be here by early next week; will know for sure then.
Rob is correct!
Engine placement can make a difference, farther back is good for hood clearance, and my engine is about one inch further foward than most Ford V8 installations (and probably several inches more foward than Rob's). When lowering the engine, be sure to lower the transmission mount to keep the driveshaft yoke angle correct, or adjust the rear axle angle as necessary.
One fairly obscure point is that the aluminum hoods give less clearance than the steel hoods. Apparently, the steel hoods came out with the factory V8s and were designed for extra clearance, even though most cars using them were not V8 powered.