bad dyno numbers.....

J

james51381

Founding Member
Jun 18, 2002
151
0
0
Newark, CA
#1
hey all. I just put my car on the dyno, 288hp and 307tq. This REALLY doesnt seem right. I think my cam is the bottleneck, but I am not sure (crane 2030). I dont have a chip either, but could that make a huge difference? I was hoping for at least 300hp. During the dyno the water temp was 205 -210, I had exhaust leaks, and the tranny has about 250,000 miles on it.

I am also pretty sure i have a vac leak but I cant find it. I did notice a plastic tube coming from the charcoal can going back to the gas tank, that was burnt in half from the subframe install. Could that be a problem? I also did not have the egr tubes hooked up, which I am sure gave a code. Could codes in the eec, change the maps and cause the car to run like crap?

thanks for any help those numbers are SAE. thanks for the help
 
#4
What is your compression ratio? I wouldn't think that it would be 8.0-8.5:1 based on your signature. I know that DSS pro-lite pistons can come in an array of compression ratios.
First, the 30# injectors appear to be too large for your combo..even 300rwhp they would be too large for. As far as tuning, what is your timing set to? Have you performed a tune up lately? 210º isn't overly hot, but it is warm enough to rob you of some power,,maybe 5 or so...who knows?
Also what does your vacuum usually stay at when the car is idling? I doubt that hose from the charcoal canister would cause a leak in the middle of the car. Does your idle fluxuate?
Not having an EGR will throw a code in the computer, and to the best of my knowledge will actually lean the car out, but w/ those larger injectors, its hard to say where the a/f ratio is. What was the a/f ratio on the dyno?

dan
 
#5
it doesnt matter if the compression was that low, it will still have spunk and wouldnt lose 40hp.

210* wont ROB power, but its not the best constant temp.

If the computer threw a code, it would be in LIMP mode, aka, RICH condition.

You should be EASY in the 320rwhp mark, IF not a little more.(with a 5spd)

exhaust leaks DONT help, so fix those ASAP.

:nice:
 
#6
sorry, I didnt update my sig. I have 24lbs injectors. The heads where decked to give me a comp of 9.47. The heads flowed just like the AFR 185 on the intake and out flowed them on the exhaust by 10 cfm. I had asked my motor guy, and he said it wouldnt be a problem for the little 306. I also dont have the long tubes anymore, I switched to unequal lengths with high flow cats. My timing is at 13* with a fp of 38.5. My idle sucks, especially when its hot. In the middle of the day, it will idle like its cold which is about 1500, then it will drop back down to 1000. I have and idle plate to help the idle but i cant get it below 750. At 750 it will idle but as soon as you rev it, it will start to "hunt" for idle or die. my AF during that dyno pull was 12.5 almost all the way through. At 3000 she went up to about 12.8-9 af.

that tube coming from the charcoal canister, is "cut" right behind the passenger front tire. I am going to fix it today, but what is it for?

the oil is perfect, and the plugs are nice........(incase you were wondering)

I dont have a vac gauge, how much vac should I have ?

thanks guys for the help

james
 
#7
I would think you have a serious vac leak judging by your idle problem..could be as simple as one of the small diameter hard plastic lines which love to break, or possible leak at the PCV or grommet..the aftermarket intakes hate to fit properly there. I would think even with that cam you should see 18pounds at least at the tree. As for timing I'd think you are good for up to 16* you should find some power there, and maybe try some rolling runs playing with FP to see if you don't pick up some power there..could need less or more...depends on lots of stuff. Just some thoughts.
 
#10
Holy crap, I dont think i've read a thread with so much WRONG information!! Let me clear up a few things, 30's are NOT too much injector, if anything, their perfect, the heads are NOT too big for a 306 (thats internet racer theory) 210* vs 180* or below WILl roba few hp. How do i know, well thats easy, I did a before and after test with a cool down and gained 4hp and 10 ft/lbs :)

Fix your leaks and go over your tune. What was the a/f??? If you dont know, you cant really tune because you dont know which direction to make changes. What was your timing at? hat cam is garbage and with those good ehads and intake, you need soemthing better. I prefer custom, but if not, look into something from comp cams. You have all good parts, but im unsure as to why you skimped on the camshaft, the brains of the engine? Your comp is prob in the 10:1 range, but you gotta ask dss, that with those pistons and a 61cc head what the comp is.
 
#13
With good sized heads and a big intake, you need a lot more cam. Give one of the good custom cam guys a call - Ed Curtis, Buddy Rawls, Jay Allen.

The plastic line from the charcoal canister vents the gas tank. You should fix it but it won't affect performance.


Grn92LX said:
Holy crap, I dont think i've read a thread with so much WRONG information!! Let me clear up a few things, 30's are NOT too much injector, if anything, their perfect, the heads are NOT too big for a 306 (thats internet racer theory) 210* vs 180* or below WILl roba few hp.
Click to expand...

Exactly. My ported TWs are "bigger" than those ported Holleys but somehow manage to make pretty good power on a little 306. My 36 pound injectors don't seem to be hurting me either. :rlaugh:
 
#14
I'm not sure about 'internet racing', but from the car's I've played with and worked on guys with 30's and above in mild street tunes usually have idle and driveability problems.

James, where did the motor peak at for HP and TQ? I agree with the others about the cam on the Holley's even though I'm running it with AFR 185's. I've not heard much good about the Holley's vs AFR's. Seems the ported holley is going to flow like crap on a small motor under 4500rpm. The 185's are almost too big on a mild built 302. AFR even recommended the 165's for my mild blower build.

Jamie
 
#15
Ranchero5.0 said:
I'm not sure about 'internet racing', but from the car's I've played with and worked on guys with 30's and above in mild street tunes usually have idle and driveability problems.

James, where did the motor peak at for HP and TQ? I agree with the others about the cam on the Holley's even though I'm running it with AFR 185's. I've not heard much good about the Holley's vs AFR's. Seems the ported holley is going to flow like crap on a small motor under 4500rpm. The 185's are almost too big on a mild built 302. AFR even recommended the 165's for my mild blower build.

Jamie
Click to expand...
:nice:
 
#16
If your heads do flow like a set of 185s on intake and better than AFR185s exhaust I don't think that cam is all that bad and I would say 280rwhp is about right but the torque seems low. Where are your peaks, is HP around 5500?. If you're looking for 300rwhp+ a 216/220 0.05" duration cam isn't going to get you there but it should make for a real fun car around town.

First thing you need to do is fix everything then get the car tuned properly before you go changing anything.
 
#17
Your alright with those injectors,I wish I had gone 30# it sounds like to me your trying to get a modded stang to idle like stock,good chance that won't happen...Try increasing your idle to 950-1000 and then reset your TPS ..Definately more timing 16-20* but only a dyno or some tracktime will tell you what's best..If $$$ isn't an issue custom cam all the way,if it is stage 2..
Also if those heads flow like you say they do those headers are probably holding you back 20-30hp across the board.....Any times?
 
#19
james51381 said:
sorry, I didnt update my sig. I have 24lbs injectors.
Click to expand...


Does anybody read before they post??? I always thought it didn't matter how big the injector was as long as the maf if calibrated. If you have overkill, that doesn't mean it will run bad does it? I know a guy that ran 42's on a stock motor with a big turbo, then sold the turbo and still runs the big injectors without any driveabililty problems.
 
#20
Grn92LX said:
Holy crap, I dont think i've read a thread with so much WRONG information!! Let me clear up a few things, 30's are NOT too much injector, if anything, their perfect, the heads are NOT too big for a 306 (thats internet racer theory) 210* vs 180* or below WILl roba few hp. How do i know, well thats easy, I did a before and after test with a cool down and gained 4hp and 10 ft/lbs :)

Fix your leaks and go over your tune. What was the a/f??? If you dont know, you cant really tune because you dont know which direction to make changes. What was your timing at? hat cam is garbage and with those good ehads and intake, you need soemthing better. I prefer custom, but if not, look into something from comp cams. You have all good parts, but im unsure as to why you skimped on the camshaft, the brains of the engine? Your comp is prob in the 10:1 range, but you gotta ask dss, that with those pistons and a 61cc head what the comp is.
Click to expand...

my af was 12.5, pretty much through out the pull. We tried 15* timing, and HP went down, so we found 13* to be perfect, with 38.5 lbs of fuel. My comp, is 9.47. and my heads after being decked have a 63cc.

I stopped making hp at 5600 and tq at 4500. I wasnt really looking into getting my car idle good, just consistant. the idle is set at 1000rpm.

The reason for the cam, is SMOG.

The heads come with mild proting from Holley. The heads only have the bowls blended and a competition radius valve job. I also stepped them up to 2.02 intake valves. decked and o-ringed. With just those mods they flowed an extra 30 cfm more.

times
13.6 @105
2.199 60ft

I also notice that if I get off the gas and throw in the clutch my rpm go up about 200-300 rpm......pretty sure i have vac leak.


thanks for the help
james
 
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