Gt 40 topend

[1quik69]

Approximately how much hp gain would a mildly ported set of GT40 iron heads with the GT40 u/l manifold, 65mm Tb and 24# injectors and matching MAF give to a stock 95 gt? We are going to stay with the stock gt cam but change the rockers to 1.7's.

 

[BlownFiveLiter]

There's several variables in trying to figure it out. What does the mild port job consist of? Just a cartridge roll to remove the roughness, or going in there with a carbide bit and opening the ports up fairly decent? Any bowl work? Figuring your average aluminum headed combo is around 280-320 RWHP, I'd estimate you'd be somewhere closer to the low range of that with the iron GT40s with a cam swap, too.

 

[legalize420]

i put down 270 with unported heads. im sure with some more dyno time to get a/f ratio dialed in it could put down a few more. i think it would be safe to say with ported heads you could get close to 300.

 

[final5-0]

With no cam or tune I'd say 250 to 260.

Grady

 

[Pokageek]

There's several variables in trying to figure it out. What does the mild port job consist of? Just a cartridge roll to remove the roughness, or going in there with a carbide bit and opening the ports up fairly decent? Any bowl work? Figuring your average aluminum headed combo is around 280-320 RWHP, I'd estimate you'd be somewhere closer to the low range of that with the iron GT40s with a cam swap, too.

Not too rack your chain but 320rwhoo? Not average. Average is like 285-290rwhp. gt40's? 260-265rwhp.

 

[Pokageek]

With no cam or tune I'd say 250 to 260.

Grady

250 MAXXXXXX with no cam no tune.

 

[urban96]

your gonna have a tuff time getting it running with no cam in there

 

[1quik69]

I forgot to mention that we are looking at staying with the stock gt cam but going with 1.7 rockers.

 

[final5-0]

Stepping up the rocker ratio is one of those mods that is highly over rated.

Yes ... they give a gain ... no doubt about it.

But it is only a hand full of extra ponies ... very small.

I see that mod as being very similar to the mid pipe.

Sometimes, peeps quickly at first go for a mid pipe change and soon there after, they learn about the advantages with LT's but they've already committed themselves with the shorty pipe.

Going to 1.7 ped rr's (the only choice for oem iron heads) influences peeps rocker decision when they step up to Aluminum heads.

Another thing about the 1.7's is they limit you with cam choice too.

I say if you have plans for higher flowing heads or a cam ..........

DON'T do the 1.7 rr thing

They don't give much extra zip
and
Why buy rockers twice

OH YEAH ... if one does 1.7's
and
then goes with TFS for a choice in heads

They WILL buy rockers twice.

Just a little out loud thinking based upon what I've seen on these boards.

Grady

 

[wytstang]

your gonna have a tuff time getting it running with no cam in there

 

[parchisi]

Stepping up the rocker ratio is one of those mods that is highly over rated.

Yes ... they give a gain ... no doubt about it.

But it is only a hand full of extra ponies ... very small.

I see that mod as being very similar to the mid pipe.

Sometimes, peeps quickly at first go for a mid pipe change and soon there after, they learn about the advantages with LT's but they've already committed themselves with the shorty pipe.

Going to 1.7 ped rr's (the only choice for oem iron heads) influences peeps rocker decision when they step up to Aluminum heads.

Another thing about the 1.7's is they limit you with cam choice too.

I say if you have plans for higher flowing heads or a cam ..........

DON'T do the 1.7 rr thing

They don't give much extra zip
and
Why buy rockers twice

OH YEAH ... if one does 1.7's
and
then goes with TFS for a choice in heads

They WILL buy rockers twice.

Just a little out loud thinking based upon what I've seen on these boards.

Grady

Where's all the smilies???