someone972

iTrader: (2)

Lately I've been thinking more about what I'd like to do long term with my engine. I've just rebuilt my 700r4 so I'm sure it can handle some more power, and right now I'm just running a stock 350 TPI so there's certainly room for improvement. I'll be getting my current setup dyno'd in a couple days to get a baseline, but I'm not expecting anything amazing.

Before I go into what I've been thinking, I'll give these requirement/guidelines:

1. Must appear stock(ish). Retaining the TPI setup is a must, there will be no super-rams or carburetors here! (Nothing against them, but just want to keep some air of originality to the car, and TPI is just cool in general )
2. This is a street car; I'm looking for more grunt in the low to mid end more than 6000+ HP power. I can't see myself going over 5000 RPM for this car.
3. Should have a reasonably smooth idle. A little lope is fine, just don't want something that has to run at 800 RPM to idle and have no vacuum.
4. Preferable to retain emissions equipment, but may flip flop on some elements. I don't think Colorado is too strict on emissions (and you'll never catch me moving to California with their abhorrent regulations).

So here is my current thoughts: I'd like to go with a reasonable set of vortec heads to bump the compression up a bit and give great flow. To go along with the heads I'm thinking something like an Edelbrock 3817 High-Flo Vortec TPI base. Something I'm not sure of is if I will need large-tube runners like the type Accel provides for sub 5000 RPM or not; advice in this area is appreciated. Siamese'd runners are out though; once again trying to keep it looking original. Also not sure if it would be necessary to go to a 52 or 58 mm throttle body. As far as exhaust, looking at shorty headers into single 3" cat to 3" exhaust catback. No idea on cam at the moment.

So assuming a get a reasonable cam, what sort of increase would I be expecting to see over stock with this kind of setup? Bear in mind that I'm more of a torque junkie than peak HP. Any suggestions or proven/well matched setups similar to mine would be great!

truckerz

iTrader: (2)

If you must use tpi, look for as@m runners and the accel base. You can have it ported and it will flow OK, not great, but OK.

Go with a lt1 hotcam, or a legenfelter 219 both work petty well with ported aftermarket tpi stuff. It is going to be way expensive though. (1100+ the cost of the aftermarket tpi and porting) The vortec heads are a good choice, but I'd look at afr 180 or pro-filer 185 heads, that way if you decide to go with a different intake later you won't necessarily need to buy head again.

You'll need a really good tune and a 2400-2800 rpm stall converter. Think yank or edge, stay away from the TCI trash.

You'll probably be around 330-360 or so hp at the crank and closer to 400-430 or so tq, at a cost of 1800-2500 depending on the heads you go with.
For some, that's way too expensive for the gains


If you search for ported tpi gains or vortec tpi build, you can get some really good info.

fokeyman

I'm not sure about your budget, but FIRST intakes are going to be expensive, but you'll be better off in the long run vs ported tpi stuff that is only marginally better and still expensive.

truckerz

iTrader: (2)

Fokeyman is correct. I forgot all about them. It looks almost identical to the tpi, just bigger. Google Firstfuelinjection. It is a torque monster. You can pick whatever heads and cam you like that fit the build, as the First intake can flow a lot of cfm.

Do a search here for First intake Builds. You can get good power estimates from people that have built their engine and had it dynoed with that intake.

someone972

iTrader: (2)

Some good suggestions to look into! Thanks.

fokeyman

Post 254 and 255 weigh cost vs typical upgrades to tpi. This was an older post, lots of info, fairly complex, non standard bolt on, but it was years ago. FIRST might have changed their design, no guarantees though. Eight page post but it's there to look at https://www.thirdgen.org/forums/tpi/...jection-6.html. Others available with search. He has another post with an adapter for older TB, FIRST's at least were sketchy. All in all, that's the route I'm going.

86LG4Bird

iTrader: (1)

I can tell you with no uncertainty that your stock 48mm TB is more than adequate for the airflow you'll push through a TPI setup.
Vortec heads will really complement the low and mid rpm capability of TPI.
LT4 Hotcam is a bad match for it. It has a lot of seat-to-seat overlap (better for short-runner manifolds) and a late IVC, which makes it want to rev where you never will.
Go with the tightest stall 9.5" TC you can get. Typically 2600-2800. The ONLY 12" TC upgrade that is cost-effective IMO is the S-10 or Vette TC.
Yank is great, Edge (Street Edge 9.5") is probably better value for what you need.


A local guy has an L98 Vette with stock TPI induction running high 12's. I'll try to contact him and get some more info, including what cam he's using.

someone972

iTrader: (2)

Hmm, I might consider a FIRST intake if I can get an adapter fabbed up to use the stock style throttle body. Like many, I'm not a fan of the look of the one it comes with and it pulls it too far away from the 'stock' appearance. I do like the sound of flowing better than a SuperRam with a "TPI" setup though. Looks like it's a pain to do fuel, egr, and various vacuum bits though. Still doesn't look as "clean" as a stock-style intake but that look is hard to keep with bigger runners and such.

EDIT: Also, I'm getting a bit concerned about emissions after reading some more. One tech got pissy with me about not having two cats when the single cat was an option, so I can't imagine what they might do if they spot anything out of the ordinary. I'm firmly in the camp of 'if it passes emissions it shouldn't matter what it's running' but obviously that won't hold up in court . Lawmakers must all be jealous of our nice cars.