Cadillac 4.5 supercharged engine (Page 2/4)
Dennis LaGrua APR 05, 10:42 AM
While the 4.9L has been boosted and has performed well (12 sec 1/4 mile times) ; I don't believe that its the best engine for adding boost. The cylinder sleeves are held in place only by the heads. Adding boost puts even more stress on this design anomaly. I cannot say that supercharging won't work as you are using a smaller blower ; I'd just be concerned with the long term reliability. This is of course is just a opinion and the long term result may prove me wrong. Very nice job on the installation.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Tony Kania APR 05, 11:47 AM
Nice work. Looks as if you are expecting a fun filled season of racing.
engine man APR 05, 01:51 PM
I would not be concerned about the sleeves as diesel engines have sleeves that are held down in place by the heads
Dennis LaGrua APR 05, 03:34 PM

quote
Originally posted by engine man:

I would not be concerned about the sleeves as diesel engines have sleeves that are held down in place by the heads



My comments are based on actual case histories of those that modified this engine. Many of them were reported here. One guy on this forum guy used a 75 hp shot of nitrous and ended up with water in the oil. It may be that a stronger copper head gasket was needed. Again I cannot say that boosting will not work but it may depend on how much boost is applied and how hard the engine is pushed. I guess that we will see, but my opinion is that this engine isn't the best platform to modify for more power. .

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

engine man APR 05, 04:04 PM
i just look at it different and i see that as a fastener problem of not clamping the head down tight enough as the fasteners are not strong enough or not enough head bolts but these engine use a wet sleeve design like a diesel from what i remember but no matter what every engine has its limits on what they can and can not take
Johns 4.9 APR 05, 04:52 PM
I am going to have to agree with "engine man" in this case. I am more concern with head bolts and head gaskets then I am with the sleeves causing a problem. But failure is part of the process and I am expecting some type of failure so I cam build the next motor stronger.
I just rebuilt his motor. Its a 89 4.5 short block with 92 4.9 heads. This yields 8 to 1 compression. The 4.9 heads have the bigger valves and ports.

[This message has been edited by Johns 4.9 (edited 04-05-2019).]

engine man APR 05, 06:02 PM
how much boost are you shooting for as i would think 6 to 8 pounds would be about max with stock pistons as i think those are just cast pistons and not hypereutectic pistons
fieroguru APR 05, 06:07 PM

quote
Originally posted by Johns 4.9:

fieroguru,
After looking at that idler bracket again, I agree with you about it being too weak. I think a steal bracket is a much better idea, good call. I think I will fab one up before I hit the track. As far as the belt path, looks good but it would hit the front of the water pump housing. Yeah, I tried at least a dozen variety of paths and brackets and the front of the water pump housing always gets in the way! Very frustrating. So I agree its not ideal but it is with in the physical limitations of the water pump housing. So as "much wrap as possible" is limited by the configuration of the water pump housing in this situation. There is still a lot of trial and error with this set-up. If it becomes a problem I will address it them. Thanks, man!
Cheers




I broke one in a N/A application, which is why it is suspect for booster application. On one swap I made a new steel bracket, on another one I reinforced the back side as part of my alternator bracket.




Here is another belt path that might work. It takes a little trimming around the timing tab and scope tube, but I used a similar belt path on another 4.9 swap:


Johns 4.9 APR 05, 06:18 PM
Engineman,
Yeah, 8 lbs is what it set up to run. I already have a new set of hypereutectic pistons for the next engine. I don't think nitros is a good idea with cast pistons for this engine.
engine man APR 05, 06:54 PM
cool keep us all updated as this looks like is gonna be a super fun project i think