Heads = zero gain
08-27-2006, 06:59 AM
#1
Heads = zero gain I sent my stock 242 heads off to a well known shop and had them do there magic, port, polish, valve job, and so on. I also went with thinner head gaskets per there instruction. I also added bigger injectors. I had 430/390 before and did 430/390 after the heads. After some tests the machine shop said I needed .005 shorter push rods, so I swapped them out. After the new push rods I had the car retuned again but it doesnt seem any faster and still gets 5-6mpg less now vs before the heads. The machine shop says thats from the bigger injectors. I can see from the data during tuning that the heads are flowing more air. I am going to re-dyno it this week to see the push rods fixed the problem. My car is no faster than before so Im guessing it isnt going to dyno anymore hp again. I am basing the speed against my friends vette, before the heads our cars were the exact same speed and now they still are. Any ideas?
08-27-2006, 07:20 AM
#3
Originally Posted by bmfcamaro
was it tuned for the injectors?
who did the port?
why the need for different pushrods?
who did the port?
why the need for different pushrods?
Yes it was tuned for the new injectors.
A very well known sponsor on here.
Was told the preload was to much, went from a 7.4 to a 7.035
08-27-2006, 07:16 PM
#5
To make things ever more weird. I raced one car I lost to before and now we were even or I would win. Then I raced my friends vette who we were dead even and now we are still dead even. But we did change his clutch,and took the TI's off his vette and installed borla's. So its possible his car may be faster with a new clutch and differnt mufflers even though the TI's are supposed to be the really good. His old clutch was in really bad shape when we pulled it out.
08-30-2006, 02:09 PM
#6
Well I went back to a smaller injector and my car seems 100% better. Im guessing the way the injectors were spraying were not agreeing with the porting in the heads. Im going to retune it today and see how it goes, but even without the car being retuned it already runs better. I re-tuned the car today on the street and its now getting 30-33mpg at 70-mph. The car is running great, but by the butt dyno it doesnt feel any faster. I have the dyno book for tonight so I will see.
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08-31-2006, 04:57 AM
#8
It sounds to me that the car was not retuned for the larger fuel injectors. With a good tune you really won't see a decrease in fuel mileage with larger injectors, unless you spend the majority of your time at wide open throttle. It is possible they retuned your car for wide open throttle, but spent very little time doing part throttle tuning. I have seen this problem in the past. Bob
08-31-2006, 05:05 AM
#9
Originally Posted by Exotic Performance Plus
It is possible they retuned your car for wide open throttle, but spent very little time doing part throttle tuning. I have seen this problem in the past. Bob
I guess I could see a tuner just tuning PE after an injector swap but only if they were retarded
08-31-2006, 05:34 AM
#10
Originally Posted by mr2guru
I guess I could see a tuner just tuning PE after an injector swap but only if they were retarded
Bob
08-31-2006, 12:42 PM
#11
The tuner is me, so that wasnt it, I do it for a living. Im not saying I dont make mistakes but I have went through the tune and even started over twice and end up with the exact same results. I put the car on the dyno again and it made the exact same hp and tq curve as before the heads and was in +-1 at peak 430/390sae. So I gained nothing from thinner head gaskets and all the head work. I did spray a 100 shot and made 523/490sae. Im so pissed that the heads didnt do anything.
08-31-2006, 05:44 PM
#12
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I run 60lb injectors and my gas mileage is as good or better than when it was stock...and my motor is stock. An A4 C5 that gets 25mpg combined city/highway...go figure..
08-31-2006, 10:20 PM
#13
Originally Posted by SAM98WS6
I run 60lb injectors and my gas mileage is as good or better than when it was stock...and my motor is stock. An A4 C5 that gets 25mpg combined city/highway...go figure..
09-01-2006, 05:47 PM
#14
Originally Posted by minytrker
I was getting 30-33mpg with 430/390 sae at the wheels.
Is that going downhill???
I only averaged 28 when I drove from Amarillo to Abilene and you don't even have to push the break when you take the only turn for 400 miles. Hell I only got 33 when doing from Albuquerque to Amarillo and that was almost all downhill (gradual).
09-01-2006, 06:58 PM
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The only thing I can think of is possibly the "well known sponsor" ported "hogged out" your stock heads and now they flow a lot more on the max flow side, but lost the velocity of the air/fuel mixture in the process. However that doesn't really explain why you didn't pick up more on the top end. Same dyno correct??? You ran it to the same Rpms etc, etc, etc? Was the car hot, or did you do the pull after the car cooled, I am lost. You should have seen some kind of gain, somewhere, DAMN !! Good luck on figuring it out. How much timing were you running before, and now?? Compression before and now?? Increased compression = increased HP >>>>>>
09-01-2006, 07:29 PM
#16
Nope thats on the interstate going flat and level. My car got 28mpg 100% stock. Ever since I tuned it, even when it was just bolt ons I have been over 30mpg. Now in town it drinks gas more that before, I get about 15mpg in town but I dont drive easy either.
Originally Posted by Genesis_26317
Is that going downhill???
I only averaged 28 when I drove from Amarillo to Abilene and you don't even have to push the break when you take the only turn for 400 miles. Hell I only got 33 when doing from Albuquerque to Amarillo and that was almost all downhill (gradual).
I only averaged 28 when I drove from Amarillo to Abilene and you don't even have to push the break when you take the only turn for 400 miles. Hell I only got 33 when doing from Albuquerque to Amarillo and that was almost all downhill (gradual).
09-01-2006, 07:33 PM
#17
Im going to do a compression check this weekend. The shop claims its impossible for the machine work to be off since its all down on a cnc machine with a +- 3cfm accuracy. They are swearing something is wrong with my car, they are guessing either something with valves or maybe head gasket. They want me to send the heads back for them to check everything out. I am at the point of just putting another set of staock heads on chalking it up as a loss.
Originally Posted by allngn_c5
The only thing I can think of is possibly the "well known sponsor" ported "hogged out" your stock heads and now they flow a lot more on the max flow side, but lost the velocity of the air/fuel mixture in the process. However that doesn't really explain why you didn't pick up more on the top end. Same dyno correct??? You ran it to the same Rpms etc, etc, etc? Was the car hot, or did you do the pull after the car cooled, I am lost. You should have seen some kind of gain, somewhere, DAMN !! Good luck on figuring it out. How much timing were you running before, and now?? Compression before and now?? Increased compression = increased HP >>>>>>
09-02-2006, 06:45 AM
#19
Originally Posted by minytrker
Nope thats on the interstate going flat and level. My car got 28mpg 100% stock. Ever since I tuned it, even when it was just bolt ons I have been over 30mpg. Now in town it drinks gas more that before, I get about 15mpg in town but I dont drive easy either.
Ahh, I was getting ~19-20 in the city until I moved to Albuquerque on Kirtland AFB. I ended up getting 4-6 mpg to and from work....
I hate the way they did the lights on base. I hate having a wife in the military there is no way in hell this is worth the $2,700 she brings home every month
.I sold the damn car because I didn't take if over 40 mph in over 2 months.
Also who the hell wants to drive a convertible in New Mexico especially when it has the highest rate of skin cancer in the U.S.
09-02-2006, 09:32 AM
#20
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Originally Posted by minytrker
Im going to do a compression check this weekend. The shop claims its impossible for the machine work to be off since its all down on a cnc machine with a +- 3cfm accuracy. They are swearing something is wrong with my car, they are guessing either something with valves or maybe head gasket. They want me to send the heads back for them to check everything out. I am at the point of just putting another set of staock heads on chalking it up as a loss.
Oh hell no. If you are buying new heads, get the AFR 205's milled to 59 cc
I guarantee you will love them. Good luck. Just say no to stock.
