4.5/4.9 Cadillac V8

Started by mgb260, December 24, 2009, 03:51:11 PM

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BlownMGB-V8

#225
October 22, 2023, 11:53:13 AM
It would be pretty easy to make a blower intake for that.

When they redesigned the lifter mount did they run the individual lifter bolts into the head?

Jim

mgb260

#226
October 22, 2023, 12:40:14 PM
Jim, They made a couple of dog legs in the valve cover sealing area due to injector locations. If a person wanted to go carb or TBI the injector holes would have to be plugged. 88-90 4.5 are TBI and 91-95 4.9 are PFI. 88-90 4.5 and 91-95 4.9 all use the ribbed reinforced block. The only carryover is the 4.5 used the old style oil pump that should be swapped to the 4.9 pump. The 4.5 has shorter stroke and longer rods than the 4.9. Everyone should avoid the 4.1 motor except a few parts like the oil pan or valve covers.

mgb260

#227
October 22, 2023, 12:53:22 PM
Jim, that reminds me. The lifter angle of the older motors with flat tappets and removing Zinc from oil caused early wear to the cam lobes. The gasket materials and Dexcool anti-freeze were issues. Also the early blocks had porosity and cracking issues. The small 4. 1 was also stressed pushing the weight of a heavy car. As far as stock net HP rating the 4.9 with 200HP and 275TQ look pretty good compared to 302 Ford or 307 Chevy that were not over 180HP and 250TQ. The 4.5 Allante was rated 220HP due to the better intake manifold.

ag1234

#228
November 20, 2023, 09:22:25 PM
I see their logic. Big mains give more rigidity and crank pin overlap.Small rods reduces I loads and makes a smaller rod ark. Plus it has hyd. rolled fillets on RJ's
                                                                                      Onward,  Art.

MGBV8

#229
November 21, 2023, 10:47:21 AM
The 1968-1971 Chevy 307 was rated 200HP/300TQ with a 2 bbl carb.
Carl

mgb260

#230
November 21, 2023, 12:07:53 PM
Carl, I meant after 72 when they went to "Net" HP. The Caddy if around pre-smog would still be higher than the Ford or Chevy!

MGBV8

#231
November 22, 2023, 10:08:05 AM
Got it.  

Not completely sold on this gross vs net HP business.
Carl

Scott Costanzo

#232
November 22, 2023, 08:18:05 PM
QuoteNot completely sold on this gross vs net HP business.

https://youtu.be/yHHLDDrIce4?si=irwtqDFP1aCyJROw

BlownMGB-V8

#233
November 23, 2023, 07:57:46 AM
He was wrong about one thing, the fan drag he showed was probably pretty close. At room temperature it would be fully engaged and only disengages as the temp of the air from the radiator goes up.

Running the fan inside a shroud and with resistance to airflow from the radiator might increase the load some, I don't know how much.

But to me the takeaway from this was that between the fan, headers, and intake system that we run on the MGB we probably don't have that much difference between the gross and net HP since we are basically just dragging along the water pump and alternator.

Jim

mgb260

#234
November 23, 2023, 10:29:25 AM
Power steering Hydraulic pump and AC compressor was also figured in the Net HP ratings. 74-84 had more smog control, ran hotter and leaner. Also had retarded timing,  so were pretty gutless.

MGBV8

#235
November 23, 2023, 10:30:07 AM
My 215 is a 1963 JN block 11:1 comp. rated 200 HP  that was rebuild back all standard.  Rear wheel dyno'd at 162 HP.  In this case, gross & net horsepower are very close to the same.

The '67-'69 Chevy 302 real world HP was considerably higher than the advertised gross HP.   :)
Carl

mgb260

#236
January 06, 2024, 04:30:59 PM
88-89 4.5 has smaller Rover sized valves. 90-91 Allante 4.5 has the same larger valves as 91-95 4.9. The Allante 4.5 has longer connecting rods and the shorter 4.9 pistons. This may be helpful for those that mix and match parts.

mgb260

#237
February 24, 2024, 03:43:29 PM
Hypothetical 4.9 build. Ported heads, cam specs similar to Ford 5.0 HO roller. 600cfm Holley carb, headers.
4.9_page-0001.jpg

mgb260

#238
February 24, 2024, 08:45:38 PM
Looks a little better spread out to show the nice torque curve.

4.9 2_page-0001.jpg
4.9_page-0001 (1).jpg

ag1234

#239
February 25, 2024, 07:14:04 PM
Is there a  flow bench report for ported  4.9L.heads ?  Using an M90 blower on a 4,9L. sounds out-matched. Any temp rise and boost data ?                                                                                                                                                                                    
                                                                                          Thanks, Art

ag1234

#241
March 03, 2024, 03:18:52 PM
Did I mention Honda H23 rods and Toyota R22 pistons ? Boring/honing wet  cylinders much easier/cheaper.( lathe and horizontal hone). Mod SBF hedders to fit.  A better aluminum head is on the way.
                                                                                                          Onward,  Art.

mgb260

#242
March 04, 2024, 12:53:08 PM
Art this page has some info on porting and blocking the heat riser on the center exhaust ports, On a very high performance build I would add steel inserts for the head bolt threads and rocker support threads. Art, are you making heads or using Rover heads with a deck plate and using your roller cam? If the later I think you would have to eliminate the distributor and use crank trigger ignition. Megajolt? Very curious as to what Jack Collins comes up with, on putting one in a MGB.

https://forums.24hoursoflemons.com/viewtopic.php?id=35746&p=4

Airwreckc

#243
March 05, 2024, 08:24:18 AM
I'm sure there's been something in this thread that speaks to the potential advantage of this over a Rover or Buick 215 build.  I'm especially curious about this vs. a stroker Rover 3.5, as I will have some parts left over from my stroker Buick 300 build (crank, heads, 4BBL intake, etc.), and also have a spare Rover 3.5. I saw mentioned the possibility of using Rover heads on this Caddy block--would the 300 heads also work?  Mostly curiosity at this point, but who knows.

mgb260

#244
March 05, 2024, 11:40:47 AM
Eric, The advantage is to the Cadillac motor. The aluminum heads are lighter and breathe better than the iron Caddy heads. I think it could be done with a special reground cam because the valve arrangement is different. It would be unique.

Airwreckc

#245
March 05, 2024, 01:59:06 PM
Jim, got it, thanks.
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