Ok, first of all please don't be prejudice because this is for my s10. This was my first vehicle I bught.... 14yrs old, sold it and actually bought the exact same truck back 10yrs later. I bught a engine froma 89 gta.

 

so I had it semi built with the 1st gen twisted wedge heads, 30 over, FIRST tpi and a a custom grind cam from comp cams. 212/224.. .487/.522. about 9:1. comp. I think,
untouched heads and gasket matched First tpi.

 

she came in at 430 trq@ 4300 & 380 hp@ 5000. after 5000 rpm hp stays semi steady to 372hp @5400 drops to 363@5500, 361@5600, 352@5700 and almost drop 10hp per 100 rpm till 324hp@ 6100rpm. hope this makes sense, what I got from the dyno only went from 3700-6100rpm

 

 

 

some of my concerns and questions are... and I hope I get some helpful info, when I got it home and was working the harness for a better fit I noticed the tps sensor clip being zip tied keeping from coming unclipped and after a closer look the connector and tps both had female ends pushing th pins out and possibly not making a good contact during dyno tuning. what type of effect would having a bad connection during tuning have on the dyno outcome.

 

also when I ordered the FIRST asked for the bigger tb 76mm. I got the smaller 69mm. I was told that after 5000 rpm it just wasn't taking in any more air . Doese the tb have something to do with it, or is it my cam or the tps ... or all of the above ... she just takes a fat tird after 5000rpm and would like to know why.

 

over 100 views and nothing from anyone....

Somebody, anybody.... answer my ?

 

Try to group your posts into 1 at a time....
You have 6 posts telling one story across 3 hrs of time...

Throttlebody may be a tad small but your cam is too small to keep pulling after 5500

 

BINGO! youll see gains going to something with about 230 duration at .050 lift BUT THAT ALSO REQUIRES a swap to a 3000rpm stall converter or manual transmission, a 3.73:1-4.11:1 rear gear and ideally a 10.5:1 compression ratio


http://forum.grumpysperformance.com/....php?f=52&t=82

http://forum.grumpysperformance.com/...hp?f=52&t=3802

 

That looks like a really well matched combo for a TPI-style intake. I wouldn't touch a thing. Drop it in and have some fun.

I used the old Twisted Wedge heads years ago and they worked really well. In their day they were excellent heads (with some quality control problems). Even by today's standards they're still pretty good.

TPI-style intakes are well known for falling off above 5000-5500 RPMs. It's not that they can't be made to flow well, it's that the really long runners are well suited to work in the 2500-4500 RPM range but they start to work against you above that point. A bigger cam can improve the top end somewhat but I've found you're going to give away more down low than you make up on the top. Your call, but I wouldn't do it. I'd run it just like it is.

 

I ran the G1 TFS heads on a flat-top 355 with the FIRST and a 218/228 cam. You're making about the HP and TQ I would expect to see with your combination. As others have said, I'd run it like it is.

The larger T/B is not going to make much difference with your combination and if you're running a typical 3rd gen exhaust, single 3" into even a very good single muffler - especially if you're running a single cat,,, going with a bigger cam will give you very little increase and kill a lot of bottom end.

However, if you have a killer exhaust system, dual 2.5s or a single 4",, going with a 228-232 single duration cam would give you around 25 more peak HP, but drop 30lb/ft torque. As others have mentioned,, depending on the torque converter stall speed,, if it's under 2600rpm,, you could slow the car down.

 

sorry for the random posting... couldn't focus with my 4yr old booger monster getting out of bed.
after talking with my builder who suggested driving it before changing anything and with your replies I decided to just do that. It should be a really nice street machine. I spoke with Ken over at FIRST (great guy by the way) he said he would just hone my tb to 76mm but said it probably wont make a difference, they recently used both tb's on a 383 and showed no difference on the dyno. He did mention that they are in the process of siamesing some runners 1", 2" etc. with both tb's and posting up the results on the website. so with that said what would siamesed runners for me with my combo?
thanks for the replies.

 

Dont waste your time with the siamesing....double check you tune if you must and go play.

 

Thats actually a very nice pull, and a good working combo. Like the others mentioned, run it it as it is.
You will be surprised how strong it feels on the street, and thats where most of your fun will be.

 

I highly doubt a bigger cam will drop that much "low end" power. We are only talking about shifting power curve 500 rpm with 8-10 deg more duration. Tpi has more "low end" than it knows what to do with . I dont think its goin anywhere with slightly bigger cam but the top end would greatly extend and that will make a quicker car. There will be more power under the curve. Tpi even the first is only good to lower 5k range for peak hp but no reason you cant extend the curve more. Just takes more duration. Your combo is fine as is for a tpi combo but if you want abit more rpm you need more cam
But in your case id really want to see higher intake lift. Keeping same duration but getting lift up near .550 or so will help increase your top end without doin harm to anywhere else. If you have 1.5 rockers go buy some 1.6's or 1.7's for that intake valve and get some power up top.

 

What is op running for exhaust?

 

In general, if you have a properly timed cam and you go bigger you're going to increase higher end HP and loose lower end torque. Peak torque may increase and you may have more overall power from shift recovery to shift point, but if the converter stall speed is too low, and it's not geared enough to give you a good terminal RPM,, the car can slow down - or at best run about the same time.

Also,, while I really like the heads for what they are,,, the old G1 TFS heads with the 12-degree intake valve are limited to around .530 lift and 235 degrees duration on a typical 21-degree piston. However,, that will vary a little depending on the combination of lift, duration, intake centerline and type and brand piston. You really have to know what clearance you have with the cam you're running to determine how much more lift you're able to add.

 

I will leave it untouched till I drive it and decide if I want to changes after. No exhaust yet I want to run true duals with an x pipe. im undecided on the muffler but am leaning toward spintech, pricey but love how vicious it sounded on a gto. what do your recommendations on size of exhaust for my combo

 

interesting......

 

what's that ...

 

i like those numbers.... i have a FIRST also and running a gm hotcam 218/228 .525 .525 lift and afr 195 heads running 10.3 to 1 compression ... i never got my combo dynoed with the new build....

 

after that long post you made about the first install way back i'm Still waiting for you to dyno it lol

 

Holley rez, three and a half years. But ya where's that FIRST dyno lol.