My C5R 427 with a ProCharger and C5R heads was suppose to run on street gas. You can imagine my shock when I went to get my car and the builder said, "Oh by the way, you'll be running 110 octane race gas". I know he did not intend for it to turn out that way so what mistake did he make that forced him to switch to race gas?

Also, within 20 miles it blew a freeze plug out of the passenger side head. What was going on? He still couldn't get it to run so he suggested meth and 93 octane. He fooled around with that for 3 or 4 months and couldn't make that work. What was going on? He would never tell me why any of this happened.

Anybody had an experience like this with this type of combo or any other for that matter who could shed some light on what was really going on in that motor to force he to go to race gas in the first place? Was this problem related to the freeze plug being blown out???

I remember that long after the motor should have been done he told me the SC was 'blowing out the flame' above 4,000 or so RPMs so they were looking for better coils. I think the real truth is he was already having some major problem that he couldn't figure our and was just stalling. It's really got me puzzled.

 

My C5R 427 with a ProCharger and C5R heads was suppose to run on street gas. You can imagine my shock when I went to get my car and the builder said, "Oh by the way, you'll be running 110 octane race gas". I know he did not intend for it to turn out that way so what mistake did he make that forced him to switch to race gas?

Also, within 20 miles it blew a freeze plug out of the passenger side head. What was going on? He still couldn't get it to run so he suggested meth and 93 octane. He fooled around with that for 3 or 4 months and couldn't make that work. What was going on? He would never tell me why any of this happened.

Anybody had an experience like this with this type of combo or any other for that matter who could shed some light on what was really going on in that motor to force he to go to race gas in the first place? Was this problem related to the freeze plug being blown out???

I remember that long after the motor should have been done he told me the SC was 'blowing out the flame' above 4,000 or so RPMs so they were looking for better coils. I think the real truth is he was already having some major problem that he couldn't figure our and was just stalling. It's really got me puzzled.

 

That's hard to anwser,but a Porcharged 427 is going to need some race gas or a nice spray of meth.

 

If your story isn't leaving out some major details, it sounds like the builder blew the motor on the dyno. Also, several people here are pushing a lot of water without blowing freeze plugs, so it sounds like a highly questionable build.

 

The builder put low comp pistons and a blower cam in the motor. We never discussed any HP goals at all. We just knew it would make good power. Something went wrong from the start and I don't know if it has to do with the C5R heads or what. I know it was the first motor he had built with C5R heads. What could have happened?

 

W/out his exact calculations on the CR it will be hard to say, but our 1,000 RWHP twin turbo is on 93 & meth no problem.

 

Sounds to me like your builder has no clue of what he is doing,
sounds like you paid too much for nothing, and you prolly have a blown motor,
may be time to start researching legal action
good luck

 

From what i can see the engine was just built wrong.Possible wrong comp ratio or camshaft.we just finished a twin turbo ls7 that made a little over 1000hp on 93octane and no meth.You shouldnt be having any problems with spark blow out either,we have put down over 1100rwhp with stock coils,part of the problem could be the tune also,if the timing is wrong that will create detonation which is covered up by using race gas.as far as the freeze plug blowing out,if he didnt use the right parts and procedeures to seal the heads properly to the block you can pressurize the cooling system under boost and blow out freeze plugs or blow out the radiator.

 

Man. I know one thing...for the coin you spent on a C5R 427 you sure as hell should have an engine builder willing to explain things, as well as admit mistakes. Not sure what to tell you other than roll up your sleeves and get some info out of this guy. Im guessing compression ratio and boost are the major factors to needing race gas..

 

No reason at all to need to run 110 octane, a good tune should cover 93 and maybe some meth no problem. Granted you will be able to have more timing and thusly more power with the race gas but saying "it won't run on 93" is just stupid.

Ick, if I were you I'd be pulling that engine out of his hands and getting it in someone elses pronto.

 

As has been mentioned, something is terribly wrong here and it sounds like you have a mess on your hands. This little 346 is making 740 rwhp and runs for two hours at a time on a road course, on 93 octane. We added methanol injection this past year to the car as the inlet air temps would start creeping up after repeated laps on the 2.5 mile road course, and the car would lose some power.
http://www.exoticperformanceplus.com...Car.php?car=40 Bob

 

Obviously we need alot more details.Something isn't right.Sounds like you have a high compression 427ci with a F1 or F2. Or someone that can't tune. Freeze plugs ussually blow out from the heads lifting -putting a ton of heat in the coolant.

 

This is a repost you've already talked about this in another thread.
edit: Did you ever get your situation resolved OP?

 

There are some details left out. The reason the freeze plug blew out is because you had a electric water pump that you wanted to turn on and off by a toggle switch and that day you forgot to turn on the water pump before you drove the car around.The car overheated real bad and blew the plug out.
The car made almost 700rwhp on very little boost. He could run 93 octane if he wanted to.I see you are still trying to get people on this board on your side. How is your case going. I guess you wanted them to settle out of court like the other 10 suit's you filed in the past,but it isn't going to happen is it!

 

The reason this build cost him so much is because he kept changing his mind.He wanted the blower setup and then after that he wanted the blower removed and go back n/a. All this work is not free. Also the money he spent isn't just on the motor alone. He put all new suspension,rearend etc. Also when this motor was built,there were only a few place's to get C5R part's. Back then these part's were going for premium price's!

 

My money is that the builder built an engine with way too compression. C5R heads are 38cc chambers! On a 427 with -38cc pistons( the biggest dish pistons I know of ) the static compression level is going to be 10.9:1. If the person put in a blower cam on a 115 LSA or higher, the dynamic compression level will be very high. To run any reasonable amount of boost on that motor you will have to run high octane gas or a metric **** load of methanol.

As said before, more details are definitely needed.

Keith

 

The engine builder know's what is going on. They have a axis machine for milling out head's and whatever. The C5R head's are a high compression head,but if they would show a pic of the combustion chamber I am sure we would see that they would be machined out!

 

Is this going to be one of those posts that the car owner acts stupid and put's himself as the victim?

 

DING,DING,I could not of said it any better!!!

 

If you hog out the chambers of the C5R head, you lose all the flow characteristics of it. You might as well use LS1 heads.

Keith