BritishV8 Forum

Well, my little project is starting to take shape...

My good friend Scott McRoberts (McRoberts Machine Shop, Longmont) helps me with machine work...


Throttle body aimed rearward for cowl induction / cold air induction.


I'm reworking the Rover fuel rail, and I plan to have it nickel plated.


Wraparound plenum wall will be TIG welded to base. There will be a flat, removable lid...


Now I have some details to work out... and I wondered if you guys might have tips.

I need to add ports for PCV, vacuum advance, and the vacuum sense line on the fuel pressure regulator... There isn't much room for threaded-in barbed hose nipples... should I use some sort of press-in, weld-in, or glue-in vacuum hose ports, and if so is there a good source for them?

What's the right physical location for the vacuum advance port? On the throttle body?

A question for people who have installed Rover EFI manifolds on Buick engines: what did you do about the thermostat bypass hose? Rover flipped it from left-side of the thermostat to the right-side. (Third photo.) Did you cut and weld, so you could use a straight hose? Source an S-shaped hose?

Curtis, Nice work. Scott and the camera person, "both" need safety glasses.  Cheers, roverman.

Put one or two 3/8"npt holes and as many 1/4"npt holes as you have room for in the base plate and a few 1/8" as well. Better to have and not need them, you can get hex socket plugs to fill the spares. If you need to put any through the side wall, tig an internal boss for it.

Consider splitting your fuel rail in the front. It's a real pain to install and remove as one piece.

Jim

"Put one or two 3/8"npt holes and as many 1/4"npt holes as you have room for in the base plate and a few 1/8" as well..."

Alas, so very little room to work with, both in terms of surface area and also height!

Yep that can be a problem. You might want to put a couple spare ports on the side somewhere.

Jim

Wow, nice stuff! I don't have anything to add but I can't wait to see it in person. Looks like you're using a GM TPS and IAC on your throttle body. How big is the throttle body? Just curious.

"A question for people who have installed Rover EFI manifolds on Buick engines: what did you do about the thermostat bypass hose? Rover flipped it from left-side of the thermostat to the right-side. (Third photo.) Did you cut and weld, so you could use a straight hose? Source an S-shaped hose?"

When I put the EFI manifold on my 215 I capped the by pass in the front cover.  You can still used the 215 thermostat housing on the EFI manifold. (I am using a Buick 300 housing that point straight ahead) The openiing for the bypass on the thermostat is below the water opening and doesn't need to be capped.  I am currently using a Buick front cover on a Rover 3.9 with the capped off by pass.  Seems to work OK without the bypass.  If I'm missing something please let me know.

"Consider splitting your fuel rail in the front."  Why bother.  You don't need to take it off that often in my opinion.

Al Wulf

Thanks guys! Excellent feedback. I really appreciate the encouraging words.

QuoteConsider splitting your fuel rail in the front.

I thought long and hard about it, but decided adding flex hose or fittings to the middle of the steel rail looked like a lot more work. I think the rail is ready to be plated now.

QuoteHow big is the throttle body?

The Chevy throttle body bore measures 72mm in diameter, which seems generous compared to the Rover 3.9's bore of 65mm except that Chevy put a peculiar stamped steel extension on the back side of the butterfly to restrict airflow. Chevy evidently used various different restrictors to tailor the throttle body for different applications. I actually have two different junkyard butterflies, with two differently sized restrictors. Some tuners trim or remove the extensions.

QuoteI am currently using a Buick front cover on a Rover 3.9 with the capped off by pass. Seems to work OK without the bypass.

Whew! It would be a real pain to modify the Rover manifold to match a Buick thermostat cover. I'll move that to the very bottom of the to-do-if-time-permits list.

With regard to vacuum ports, I think the best way to make straight NPT-to-hose-barb fittings work might be to weld a couple little blocks onto the bottom of the plate and achieve 90 degree turns by drilling perpendicular pairs of holes. That's a couple more widgets to have machined before I visit the TIG welder.

What about the trumpets, are you leaving them the same length ? Std manifolds have them mounted at different length to compensate the difference in port length ? Also, what will be the distance between the trumpet and the top of the plenum, looks like there is very little space.

Yes, I'm aware of the trumpet issues... as reported here:

QuoteThe inside diameter of each trumpet is 3.81cm. The cross-sections of the runners in the cylinder heads are significantly smaller, but in the intake manifold the runners quickly transition up to round cross-sections of about 3.8cm diameter each. The average total length of all eight runners measured from intake valve to open plenum is about 38.75cm. (Runners 1 and 8 are approximately 41cm long. Runners 2 and 7 are approximately 39cm long. Runners 3 thru 6 are approximately 37.5cm long.)

All eight trumpets will have to be trimmed, but how much they'll be trimmed hasn't been determined yet.

Equal length runners (from the port) aren't necessarily best, as McLaren demonstrated back in their Can Am days. McLaren had a lot of dyno time to play around in, and their conclusion was that deliberately varied runner length could widen the top of the torque curve.  I wonder if there's a handy trick for individually optimizing them. Comparing exhaust gas temperature?

My machinist friend has suggested that we might roll out the tops of the trumpets to a larger radius and wider bell-mouth.

I've been reading a bit more about runners and trumpets. If anyone is interested, tmoss's posts <a href="http://eectuning.org/forums/viewforum.php?f=17">here</a> might be interesting.  In one of them he links to this document about plenum size and runner length: <a href="http://eectuning.org/forums/download/file.php?id=570">Plenum Size and Runner Length</a> Interestingly, that document includes some runner volume suggestions. If you extrapolate to get from 302 Ford numbers down to Buick/Rover numbers, it seems to be saying that a good target for total runner volume (valve to trumpet tip) for a 3.5L engine might be between 342cc and 420cc per runner. Based on a quick estimate, I think the stock Rover/GEMS system comes in around 442cc/runner on average. I'm almost curious enough to cc them accurately.

---

I'm about ready to start installing vacuum ports. I realize now that I'd forgotten about the MAP sensor, so I'll add one more 1/8 NPT threaded hole for that.

Question: How much condensation accumulates in an EFI plenum? Crankcase vapor? Fuel fumes? Moreover, how concerned should I be about those contaminants affecting or damaging my MAP sensor? I'm thinking an extension to put the MAP port above the floor of the plenum might be a good precaution.

Curtis, I'm sure you've seen these...
http://www.actproducts.co.uk/shop/ti022a-superflare-trumpets-39-45l-p-350.html

Yep... and I saw the price tag too!  (197 pounds = 311 dollars)  A wise guy once told me: "There's a time and a place for everything." but I'm skeptical about the inside of an EFI plenum being the right place for carbon fiber bling.

Whoa!!  I overlooked the price.... was searching and ran across it one day. Hadn't really looked at it close. I think other options would be in order.

Making slow but steady progress!



Fuel rail is complete and has been electroless-nickel plated.  New air cleaner housing is complete. (Intake air temp sensor will enter from cabin side, under the dashboard.) TIG welding on plenum and intake manifold is ~90% complete. Welding inevitably causes a little warpage, so I brought the plenum back out to my very good friend Scott McRoberts (at McRoberts Machine Shop) to have gasket surfaces (to Rover manifold and GM throttle body) fly-cut flat.

Next I'll take the plenum back to the expert welders at Peterson Fluid Systems and have them weld on bosses I've made for PCV, MAP, and vacuum advance connections. The sides of the plenum will then need to be cut down at least a half inch, and at the same time a ledge will be cut into the thick back wall. That will provide a sealing surface for the lid. Due to bonnet clearance issues, the lid can't be as tall in front as the throttle body is at the rear... Scott and I have a plan for a billet aluminum lid designed to match Buick-style valve covers. Trumpets will probably be tuned/trimmed/staggered/whatever... but I haven't decided on lengths yet.

Fuel injectors have been cleaned and flow tested, and should be back on Friday. Fuel tank with built-in high pressure pump is scheduled to arrive in January.

I guess it's time I start tracking down MegaSquirt parts.

It's looking great Curtis.  You planning to have it done in time for BV8 2013?

Thanks. Yep... Omaha or bust!

Looking good Curtis. Just curious, what did you have to pay to get your injectors cleaned and tested?

Jim

$16 each.  I chose this gentleman, and am very pleased with his responsiveness and excellent communication:

http://www.mrinjector.us/index.html

I realized you were building a test rig just hours after sending my injectors off!

That's OK Curtis, I'm not up and running with it yet. It looks like a good process he uses as far as I can tell and the ultrasonic cleaning is something I will add. How many data points did he give you on the testing? Was there a graph generated? What I've seen is that only testing for full flow is not enough, you need to know what it does at lower flow rates. After all, most of your driving is at part throttle.

Jim

I mailed them out Saturday and hope to have them back tomorrow. When they arrive, I'll scan and post the test report.

QuoteHi Curtis,

Your injectors arrived and have been serviced. There were several that were stuck closed but that isn't unusual for injectors that have sat with old fuel in them. They cleaned up well and are well balanced. I have found these Lucas disc injectors to be very well balanced when clean. Another benefit is they are very quiet. They hardly make any click at all. Your two spares are in a sealed package marked "spares" for storage. There is also a full report in the package.

I'm shipping them back USPS Priority. You will receive an email with conformation and tracking.

Thanks for the business! BIll

Test report:

OK, so I would guess that maybe the mention of the dynamic tests that they run would be the cycling test which would apply to part throttle conditions. To my mind the partial flow is every bit as critical as full saturation flow. In fact, if the injectors are correctly sized they will never quite reach full saturation and will always be operating in the cycling mode, which means the pulse width is turning them on and off continuously with the pulse duration controlling the length of time they are switched on, thereby controlling the amount of fuel that is delivered.

In all probability your injectors perform uniformly in the cycling mode. However, I have seen sets of injectors that did not and in fact I have a set on the bench right now that preliminary tests indicated horrendous variations even though the full flow is pretty uniform. Hopefully a good cleaning will straighten them out but my fear is that the vendor may have made up a set of 8 by combining 2 sets of 4 from different engines and they may be quite different in their fuel delivery curves. A good cleaning followed by the cycling test should tell the tale.

Generating a fuel delivery curve is a good deal of work. You have to determine the flow rate at each point in the graph, which means a timed test and a fuel measurement for each injector. So for eight injectors and just a four point graph which is very rough, you have 32 measurements to make and enter into a program to generate the 8 individual curves, one for each injector. It also means having an injector driver that can deliver the appropriate pulses to all 8 injectors at the same time and is set up to allow you to select the right pulse width. That's a pretty sophisticated flow bench. Mine has the capability to do full saturation and a cycling test that gives about 1/4 to 1/3 full flow, although I really don't know what the pulse width is. The next upgrade will have selectable pulse widths, possibly with a digital pulse width readout but I won't be needing that right away. The cycling test does a pretty good job for now, and I can get back to improving that once my car is a little closer to being driveable.

OTOH, if I happen across a digital display that can give a pulse width measurement I just might have to do the upgrade. This is the one I'm using for the test interval:

http://www.ebay.com/itm/280892518436?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Maybe they have one that can read in the millisecond range. Injector pulses run from about 2 milliseconds up to about 28 typically. It takes at least 1-2 ms for the injector to open (disc type injectors are a little faster so they have a little better dynamic range... at the cost of lower maximum flow capability but perfect for a 3.5) and beyond 28 ms we run out of injector time at high rpm. Once that happens no more fuel can be added without increasing rail pressure.

Curtis, you definitely did the right thing having your injectors cleaned and tested. The test results show that very clearly.

Jim

I have injectors off of two different Rover engines. They're all nominally "Lucas" injectors, but actually only one set has Lucas logos molded into them and the other set has Seimens logos. The Lucas ones had green stripes painted around their middle, whereas the Siemens injectors were all black except for a green plastic clip near the top. Exterior shape/dimensions were identical. Some of the Lucas injectors were banged up, so I had the Seimans injectors cleaned (plus one of the Lucas injectors as a spare.) What I think I've learned from your post, Jim, is that I shouldn't mix the two brands on my engine, even though they all flow 58cc/15s wide open because they might not all flow the same at partial throttle. Cool.

Next issue... how to "optimize" the length of the trumpets. The flared steel tubes all start out 100mm long. Rover installed them into recesses of two different depths... so the trumpets for cylinders 4,5,6,&7 appeared longer:  


Why? Apparently to crudely equalize overall intake port length. Note how some ports in the intake manifold are longer than others because they cross over...


The bottoms of my trumpets are flat against my Rover intake manifold, and my plan for some time has been to trim some of them. The longest trumpet(s) will be left 100mm.

Some time ago, I crudely shaped lengths of copper wire to follow the approximate center-line of each port and then I straightened and measured the wires. Based on that exercise, I expect the trumpets for cylinders 1 and 8 should end up ~55mm long and the trumpets for cylinders 2 and 7 will end up ~75mm long.

Would it be better to "cc" the ports instead, and equalize volume instead of length?

I don't have an extra set of Rover 4.0 heads around, so it's not convenient to cc their intake-side ports. Anyone know where to get cc numbers for them? (I guess I could cc my spare set of Buick 215 heads...) Suggestions? Opinions?