This summer I will be shooting for 300hp or a 12 second quarter mile. The car is an 85 shelby charger with a rebuilt 2.5L turbo engine.
My plans are:
+1 mm oversize valve ported head
fully ported exhaust manifold
ported 2 piece intake manifold
super 60 turbo
+40's
walboro 255
new custom cal
huge FMIC
20 psi max
My question is which head should I run. swirl or g-head?
Is a 2.5 and a g-head a good combo?
The car will be a daily driver so it needs to be streetable and somewhat reliable.
The word on the street is that the G-Head is tough to tune for a 2.5L. It's hard to keep the EGTs under control while avoiding detonation at high boost. I'd recommend a swirl.
First of all, if you want more streetable go with a 2.2L.
I've had a high boost G headed 2.2 and a G headed 2.5, and swirl versions of both as well. The 2.5 had WAY MORE traction issues no matter what I did, and as already mentioned by russ I could NOT get EGT's under control with the 2.5L. However, with the G headed 2.2 it was glorious. Egt's were 1500, and traction was soooo much better on the street and at the strip. This was in a G body, still WAY plenty of torque because I have the 3:50 final drive so in an L body you really really really want to stay away from a 2.5L. Trust me.
I myself just ditched my 2.5 in my shadow back to a 2.2, never again will I run a 2.5 in anything except my heavy dakota and perhaps if I own a turbo mini someday. Even with a ported head, huge turbo, 3'' exhaust, huge FMIC, etc it ran out of steam at 6000 RPM. My old 2.2 liked to rev to 6700, much better for higher RPM's when you are street driving.
Is it really worth it that much to go to a 2.2? I just rebuilt the 2.5 (havent even put it in yet) and by the time I'm ready to do the modifications it should be broken in. I just dont know if I'll have the money to throw into a new shortblock. But, if performance will really be THAT much greater then I might reconsider.
It's totally up to you, but I just tore my 3000 mile 2.5 engine out of my car to go back to a 2.2!
Especially in an L body, you will have MAD traction issues with a 2.5, plus since we are recommending the swirl head thats even more torque.
It will be a lot of work though since you already have the engine built, and like you said the money issue too. If you don't got the money, it kinda blows the whole thing anyway. Run what you got I guess since it's already built.
Ya, I think Ill make the decision when the time comes. So the general concensus is 2.5 + g-head = bad?
Here's an example. .040 2.5 with a stock G head, stock cam. Ported 1 piece intake, ported exhaust manifold. 50 trim hybrid with stage 3 tubine, SRT4 intercooler. All in a Shelby Charger with an auto. The car ran 8.30's at 85+ mph @ only 18psi. Easily a 7 second 1/8th mile car with more boost, and was running a basically stock 2.5 with a nice turbo.
Not bad, I made good power with it. But, it's not very tunable. I could not get EGT's under 1700 at 20 PSI boost no matter what. I had the CEL flash on knock enabled, and at 15 PSI boost I could put in enough timing for it to only hit 1600 EGT's but anything more than 15 PSI and it was 1700. This is on pump 93 octane.
But as we see in your sig, you went back to a 2.2....?Originally Posted by glhs875
I don't know what the EGT's were on the above combo, but I built the engine and it's still running after over 2years. Seen the car at the Drag strip tonight.
Not my car. It's one I built for somebody.
I like my 7500+rpm 2.2 in my GLHS
Ahh, cool.
Yeah despite 1700 degree EGT's in my setup I never melted a piston even with the stock Mahle's.
Don't take me wrong, I like my 7500+RPM 2.2 8V in my GLHS.
My current 2.2 thats getting dropped back in is built in hopes for about 7200. I built it to the same specs as my old G headed 2.2 which liked to about 6700 with a stock cam, now I have one of Simon's S60 roller's.
That should help! The 7500+ was with a Taft S3 cam. I was spinning a stock 89T1 cam to 7200rpm. Did some upgrades to the head since then, mainly for valve float issues. Now if I can only get it running again.
My current 2.2 thats getting dropped back in is built in hopes for about 7200. I built it to the same specs as my old G headed 2.2 which liked to about 6700 with a stock cam, now I have one of Simon's S60 roller's.
Err actually now that I think about it the 6700 was also only with a super 70/ .63 stage 1 turbine. Now I have a much larger hybrid with a stage 3 turbine.
Matt,
What kind of EGT set-up were you running with the high EGTs? Guage probe type and location?
Westach, probe in the number 4 runner. It works fine though because it's the same one and same spot that was registering 1500 EGT's when I had the G headed 2.2L.
I used to have a G-headed 2.5 in a daytona and loved it. It was the absolute best setup I have ever run. It was a bit difficult to get a custom calibration set up for it but once I got one it worked great.
If you have traction issues with the 2.5 it is simple to run a calibration that has staged boost control. I had an EGT readout in my car and never experienced high EGTs.
Perhaps those people with EGT issues had different cam timing than I did. I was using an 84 slider cam with a round tooth belt pulley. That must have advanced the timing some.
It is true that that combo does not rev really high. Mine ran out of power around 5500 rpm. All of that low RPM torque is a riot to drive around town. Probably even more fun in a light weight charger.
I can say I have a 2.5 with a swirl head in my 89 baron and i love it. I haven't had any problems with it at all. This is combined with a mopar performance computer, +40 injectors, turbo's unleashed built mitsu, upgrade cam, and my foot in the floor!!
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