00PewterSS

iTrader: (3)

This spring I installed PRC as-cast heads, LS6 intake and converted the fuel system to E85. I retuned the car for E85 and based on the wideband etc. everything looked ok. Car drives good and seems strong.

Today I went to the track and the car is slower than before these mods. Previously with just a Torquer V2 and supporting mods it ran 12.4@119mph street tire 2.1 60ft. Now, with the heads, intake, E85 I could only a 12.8@115mph same 60ft.

Car was hot so I couldn't do much tonight with it. I'm brainstorming what could be wrong to lose maybe 80hp and the car still drive good.

Wrong pushrod length (I think this would cause other problems)
Not firing on one cylinder (possible, I'll pull the plugs)
One injector clogged or otherwise not working (I could hear each of them ticking)
Cracked ringland (no smoke, no oil contamination)
Bad tune (seems unlikely at WOT to cost that much hp and the wideband is ok)
Vacuum leak (this is a real possibility, I have noticed something like an exhaust leak and this was a used intake)

I'll pull the plugs tomorrow. I will also try to identify any possible vacuum leak.

Anyone with a similar experience, or other ideas to try?? I expected to be pushing 11's not running the same as I did with only headers.

Thanks - Brian

LLLosingit

iTrader: (4)

Are the combustion chambers the same size on the old and new heads? Tune would probably need adjusted for better flowing heads. Specs on old and new heads? Compression ratio? You might want to pick up a good temperature gun. They are great for comparing cylinder temps, By comparing temps you can help narrow down the problem cylinder/injector is there is one.

HCI2000SS

iTrader: (2)

Who tuned it? I see you are in Hartland. I'm in Fenton btw

Rise of the Phoenix

iTrader: (27)

I'd check the plugs and also check for compression in all cylinders. I bet you're down a cylinder or two.

mikesimpalass

Just a couple of ideas, like you said, it could be a vacuum leak. Do you have a scan tool/ hp tuners? See what the map sensor is reading. Also, before you dig in too deep, take an infared thermometer and check the temp of each header tube, that will give you a good idea if you have a dead or weak cylinder. And more importantly, which cylinder it is.

Full-Force

iTrader: (11)

When you say wideband is ok, what a/f are you seeing? What were you seeing before?

MaroonMonsterLS1

AFR for pump gas and for corn are very different. I hope you had your wideband setup for lambda or AFR scaled to corn. If not, you're gonna have a bad time.

00PewterSS

iTrader: (3)

Stock heads were on the car, switched to PRC as-cast heads milled so now it is 11:1 compression.

After the cam the car was tuned at CARS Waterford originally, I forget his name but I'm not impressed with what they did. I used HPT to modify the tune for E85. The tune is using the MAF running in open loop and CARS did not adjust the VE table at all. They adjusted the PE table / spark etc. So the VE table is still wrong as I have not went back to fix this. The AFR at WOT is fine, I'll log it again tonight, but it is around 0.8 lambda which is ok for E85. I never had a wideband on the car before, so I do not know what it was previously.

I do have HPT and will pull the plugs tonight. I would expect if it is down a cylinder I should be able to see this in the plugs.

At this time I'm still inclined to think it is a vacuum leak at the back of the intake, I just don't know what impact this would have.

Brian

HCI2000SS

iTrader: (2)

When I purchased my ride it had a tune from CARS, and it was horrible lol. My new tuner is in Milford and has been phenomenal.

On a different note you ever head to Bakers car show on Sundays? There's also a big one in Hartland this Saturday as well

00PewterSS

iTrader: (3)

The infrared gun looks like a fun tool, I think I'll pick up one of those today! Pulling the plugs sounds easy but some are a PITA, I'll check temps first, thanks for the idea.

Yeah Sean at CARS is who tuned it and now I can see with HPT the minimal work was performed.

I talked to someone at Camaro Superfest that also had their car tuned by Jesse. Mike or Mark, I'm bad with names. My neighbor was a calibrator for crate engines so he has helped me, but doesn't have experience with cobbled parts like my car.

I haven't been to the Bakers show this year. I'll be at the car show this weekend at St Johns church. I planned to bring this car, depending on what I find wrong, but we will bring our LS4 Fiero.

HCI2000SS

iTrader: (2)

Yep Jesse is the guy. I was at the Superfest as well. Might have bumped into you. I'll be at the St. John's show as well

Full-Force

iTrader: (11)

What is the wideband saying your a/f ratio is???

Sales3@Texas-Speed

iTrader: (2)

If you did not change pushrods when swapping the heads, that's part of your problem. On average the aftermarket casting PRC AsCast heads need a .050 longer pushrod than a stock casting due to the thicker deck surface. We still always recommend everyone to measure for proper preload with a pushrod length checker to be 100% sure on the length that you need.

Lonnie

00PewterSS

iTrader: (3)

-Lonnie,

Heads were milled for 59cc... I bought 7.45 pushrods from TSP since that was the recommendation. Though I didn't check that they were correct. I think I'm good, but I'm not ruling anything out. I don't hear a lot of tapping, pretty quiet actually. Any other sign before pulling it apart that the pushrods are too short? Thanks for the feedback and great service when I purchased my stuff.

00PewterSS

iTrader: (3)

I'll log some more data. But the data I have shows about 0.8 lambda at WOT. This should be fine for E85.

Taprxxt

I just had the PRC AS-Cast 225 heads installed on my '00 WS6 with the TQRV4 cam. They were milled to 60CC ... pushrod recommendation was 7.475 which is what I went with. Everything has worked out so far. Not sure if that helps at all but I figured i'd chime in given I also got my H/C package from TSP.

Sales3@Texas-Speed

iTrader: (2)

With your heads being milled, on average, that seems to be the length that we see works 95% of the time. Though I would still measure just to be 100%. I was thinking you used the stock length pushrods from your previous set up. I could definitely see that being a problem. With the pushrods you used I wouldn't expect that to be your current problem.

Lonnie

JoeNova

12.4 to 12.8 is not an 80 HP loss. Maybe 35 hp.

Get a pushrod length checker and work on that tune.

00PewterSS

iTrader: (3)

12.4 was before heads and intake. Heads and LS6 intake should be good for 45hp. That is where my guesstimate comes from. So I agree with your estimate as well.

Full-Force

iTrader: (11)

Im assuming the DA was same or close? If its real high compared to real low that can be a half sec difference.