kad5118

hello everyone i have a question to those that have actual experience with fully ported and hogged out tpi intake systems,I have a l tpi intake setups that consist of slp runners, stock tpi intake manifold, stock upper plenum and.I am having it fully ported and siameased.The runners a getting siamease all the way through,the lower intake will get siameased half way through the intake ports,as well as the intake port part of the intake will be gasket port matched.the is using felpro 1204 gasket as a guide.the upper pluenum runner port will also be enlarged and siamease to match the fully ported and full siameased runners.

This intake is going on a stock 91 l98 engine thats in a 91 ws6 gta.the question i have is how will my stock l98 respond to my modified tpi intake.

PhoenixFirebird

iTrader: (2)

I wouldn't get the base siamesed personally, even though that's what mine are. Not on the car yet, so I have nothing to report, but eveyone else says it's better off being individual runners.

kad5118

ok well do you lose torq or does it like screw up the performance of the engine

fireturd350

iTrader: (8)

Debates have been going on this forum for well over 10 years. Some say it messes up the air/fuel mixtures others say it doesn't. Just search around and you'll find plenty of info.

That being said just about every combo should act differently.

The main thing about TPIs are they were designed with the long individual runner design which builds torque on the low end which is great on the street.

If anything port matching would be better than nothing. The stock base is pretty restrictive on the runner gasket side. If I remember there is normally a good amount of extra casting left over inside.

PhoenixFirebird

iTrader: (2)

It kills the wave harmonic tuning effect that single tube LTR systems have. As for performance effects, I would guess its more power than stock, but less than big tube individual runners. The main thing is it shifts the powerband up as more of the divider in the base is removed.

kad5118

I have looked around the forums for the answer but.they all seem to have one thing in common they dont mention what the out come would be on a stock tpi 350.I dont have a 383,a 368 sbc,355 with a cam none of that,but i do have a 408 sbc with same setup but with the edlerbrock base intake,that setup also will get the mega port treatment aswell.But I have a 350 stock with 137,000 miles that this setup will run on.can any one else on this forum give me a detail answer thats running a ported setup on their stock 350.thanks

thewhitestripes

I have your exact set up on my 88tpi: ported base and plenum, ported slp runners on a stock 350 with just little mods like gutted air box, plugs an wires, bosch 3 injectors, exhaust ect. Unfortunately I was swapping out my 305 to a 350 when I had the port work done so I don't have a side by side comparison. I'm happy with it though. If I were to do it again I might have bought a HSR for the price of runners an porting work. (roughly 900 bucks) ad then had the HSR ported in the near future. HSR's are much easier to work on too. Just a thought if you wanted to explore that route.

Johnny Blaze

iTrader: (15)

Not much to gain by hogging out the intake for a stock engine, IMO. Now if you are going to ad a bigger cam and heads, then yes.

kad5118

well i guess that i am lucking the guy is not charging me a lot for the extensive port work to my tpi setup,Did it seem like you lost torque down low and made more top end power ?

cuisinartvette

the car is going to be a dog in comparison you wont like it
Be real lucky and save your money.

thewhitestripes

I think I may have lost some torque. Not much though and deffinatly have more high end power which is nice. It lets the tpi breath better in the higher rpms. The porting cost me like 600 give or take which was costly. I just like the stock look of tpi too. I read an article that a ported tpi and slp runners net more hp then a stock HSR. it may cost a little more but a tpi can run with the big boys for sure. I've seen build threads on here that make upwards of 700hp with the right combo of parts

kad5118

a tpi making 700 horses or close to that power i never heard of that before,I never heard of a tpi making over 530 horses or more even with the small big cube inch motors.Im sure they had some type of assistance of some short.maybe a supercharger or turbo or maybe even nos to make that type of power.I know for sure a tpi engine cant make that power in n/a form.I would like to see that article if it is possible.

Johnny Blaze

iTrader: (15)

I've never seen a na small block of any sort mke 700hp.

red rock

iTrader: (2)

Porting out the plenum, runners, and intake are fine if you are planning a rebuild in the future with bigger heads and cam. The stock intake can't hardly be ported to equal the porting of an aftermarket intake such as a Edelbrock etc. With that being said, you will loose some low end torque with a bone stock tune, and factory torque converter, trans. shift points, and the factory gears in the rear. In order to compliment a porting job, you have to look at all factors from the motor to the wheels. In most cases, just freeing up the exhaust, air cleaner, fresh plugs, clean injectors, will net you a better hp gain with less work involved. I'm not trying to discourage you, i just don't want you to expect big seat in the pants gains, that won't be there until you start getting into the motor with pistons, cam, heads, injectors, custom tune, etc.

cuisinartvette

Oh theres plenty of them out there running around Gen1 too

VincentZ28

iTrader: (2)

Porting the stock manifold and porting the runners will give some gains in the low-mid range up to 5100. With a set of Dyno Don's Headers,dual cats and 3in Magnaflow cat back your gains to the wheels will be 260-280whp depending on the year and rated factory HP. Up to 350wtq. Us SoCal dyno kings know that for sure.
An 89 GTA L98 G92 made 251whp with just Dyno Dons exhaust and tune. If you don't follow this route you will not see the same gains.

Johnny Blaze

iTrader: (15)

Id love to see some.

Johnny Blaze

iTrader: (15)

With a stock cam? That's very impressive!

VincentZ28

iTrader: (2)

Yes with a stock cam and heads.

thewhitestripes

I can't find the article but I saved the picture of the car. Nobody said anything about naturally aspired motors.

I think it may be twin turbo. And puts over 700hp to the wheels.
And response to what others have said, theyre right. Don't expect huge gains. I thought of it as an investment for the future. You wil get much more out of the motor when you go for a heads, cam combo. Just like everything with a motor their is more then one way to reach your goals. Some cheaper then other but I guess it's all about preference. I like the tpi so I stuck with it. To each his own.

kad5118

I dont really expect hugh gains with the just getting the intake ported I want to have a rough I deal what to expect I may use this same intake on my 408sbc.or I may sell it in the future.

But one thing that does suck azz is my wife blow the head gasket on the l98 on accident.so now the head gasket has to be changed and also .I may need to get a new head if need.and what really sucks about it is that the thermostat was the cause of the engine overheating and on top of that it was a new thermostat at that just a faulty one.who knows maybe it was made in china.so now that has to be done.so now is a perfect time to add full 1.6 ratio rocket arms to the heads now and some shorty headers.

cuisinartvette

Use a different intake on the 408 they need all the air they can get

PhoenixFirebird

iTrader: (2)

Anything bigger than a 383 I would suggest the FIRST system. You could make your own runners and do major work opening up an aftermarket base, but at that point it would be more efficient to get a FIRST for those kind of cubes.

VincentZ28

iTrader: (2)

Or a Miniram even a HSR

oldguy

Will an Edelbrock high flow tpi base plate and runner intake give me much gain over my stock 91 LB9 intake ? I already have hooker headers and a 3 in hooker aerochamber exhaust set up on the car.