I'm wondering if anyone out there has ported their TPI intakes (plennum, runners, and base) and put it back on stock heads/cam, did it make any difference at all? Yeah I did a search hehe, didnt get any personal experiences. I read alot of posts where people say its not worth it since stock heads/cam kind of stink, but has anyone tried it? I imagine Siamesing the runners and/or base would be a bad idea since it would shift the powerband higher with stock heads/cam. But a little more airflow sounds like it wouldn't hurt. Just wondering if it would be a waste of my time. I came across another TPI intake and before I polish it up and install it I was considering porting and port matching as much as possible.

 

Not exactly what you're looking for but is some experience with an upgraded TPI on a stock heads/cam car. I replaced stock runners and base with a cleaned up Accel intake and AS&M LTRs. So far I'm disappointed. I've only had it to the track once since the intake change but the trap speed didn't improve at all (97-98 MPH), so I didn't see a 20-30 HP increase that's advertised. Hoping things will pick up with the cooler weather and some more PROM work. Upgrade the heads and cam and I'm sure things would be different.

I do believe it's worthwhile to clean up the stock base with some sanding rolls and smooth the flanges inside of the stock runner tubes, even with stock heads and cam. This is my backup plan if I can't get the aftermarket to earn it's keep.

 

Mine is an after market setup too but .....

Even with the new intake and a lil better cam ...I still didn't see muchof an increase in top end ....just a less harsh wall you run into up top . Another guy on here ported and siamesed his runners all the way . He got more power up top , but he did a cam swap aswell.

If you are bored ... i would get the heads done too ...and maybe flowed ( to better match a cam) .

 

Hey thanks for the experiences guys, it helps alot. So not much (if any) of a power gain on stock heads/cam. Did throttle response change at all? I know changing the heads/cam is the way to make more power, but for my 89 IROC right now I dont want to mess with it (building another motor on the side). Just debating what I should do with this extra TPI intake. Thanks again guys. If anyone else has any experiences I'd love to hear it. Thanks!

 

i think you will see the biggests gains if you add 1.6 rockers to the mix.

the TPI intake with a port job will flow better than the heads but it helps alittle bit. 10-20 probly i would think. but combine that with AFPR and 1.6 rockers, then u can take advantage of that extra air.

88TPIformula or something like that has a superram on his car with AFPR and 1.6 ratio rockers on stock heads/cam L98 and he goes 13.4 at 102mph

 

I couldn't tell a difference. It was great before the intake swap and great after. It's still a challenge to hook up on street tires. If there was any torque loss, which I doubt, my converter and gears mask it well. Just didn't show the gains above 4000 RPM that I would like to see.

 

whats it mean when "siamesed his runners"?

 

These are siamesed runners, note there is no wall between the individual runners in each pair.

 

so origionally they were split into indvidual and you cleared it all away correct. got ya

 

Those are SLP runners.

Originally they had about a 3/4-1 inch deep notch in between the runners that was open. They are siamesed about next to nothing when u get them.

He ported them out and deepened the actual "siamesed" part of it. He just went farther than when I did mine :-)

SLP runners are the best bang for the buck out there if u have stuff for porting like the bits and sand paper rolls.

later
Jeremy

 

If I understand correctly, when you siamese the runners (and/or base) you are modifying the setup to act more like a short runner style intake (aka LT1, HSR, etc) versus the stock long tube runner style intake. So this would result in more power at higher RPM's (raising the powerband). I imagine this would not be much use with the stock heads/cam since they also attribute to the infamous TPI wall of 4500-4800rpm where the power falls off. Am I right in this assumption? I thought it might be possible that porting and port matching everything would result in a little more flow which might be usable by the stock heads/cam to make a little more more power, like 5hp or something. But it dosnt sound like it makes much of a difference. Maybe I'll do it anyway for good measure. Do a few of those low hp mods and it adds up ...

 

Kev91camaro or something like that had a thread here going on . He did the stock 083 heads ( ported alot) then did the intake ( fully siamesed ) with a hotcam and got over 300rwhp

So if you ported the heads too you can see nice gains with it all . I am sure if I had my heads ported ( only cleaned them up and rebuilt them) I woulda seen better up top performance . If you got a spare and the time and you like donig it ..Give'r

 

As stated, if you're going to the trouble to swap intakes, pull the heads and clean 'em up. Atleast blend the bowls, but gasket matching is always a plus. If you don't need the car right away, then you should deffinitely do it. That way if you get tired of grinding/frustrated, you can just walk away for a while. I've done bowls in 2 evenings. One evening per head. Definitely worth the time. I wouldn't get to worried about the siamesed base, just smooth it/gasket match it. Siamese the plenum(at the runners) roll the edge into each runner(round off the edge between tubes) and cut out the "walls" behind the throttle body. If you do the heads and the intake, you'll notice the difference. The only real difference in cost will be a set of head gaskets...

 

That makes sense but for my situation I'm building another L98 on the side w/ better heads, cam, and aftermarket intake. So I dont really want to dig into the L98 I have in there now with stock iron heads, its not gonna be worth my time. But I do have this extra TPI intake I want to polish up so I'm considering if I should do anything else to the intake before putting these parts on. I'm probably only going to do the runners and the plennum, not gonna remove the base.

 

hey i know that guy......lol

13.21@104.63

 

I ported my stock runners pleuim and base added a AFPR. I didn't go all out on my runners I just removed the lip from each port, base and pleuim i cleaned very well. I felt a pretty good differnce and data loggin showed my shift points hit 5100-5200 rpm. I'm still tuning my chip for the lean mixture problwm I'm having . Only catch is I have a 88 vette. The vette have other preformance parts the come stock to contribute to the mods so that might be helping. I did lose a little bottom end. but i can still do a burn out down shifting into 1st gear going 30 mph on 2.59 gears hehe.

 

Why not do it? It's Free

Don't be surprised if its only 10-15 hp, but if you do other mods with it, trading 15 lb ft tq at 2000 rpm is worth 15 more hp at 400 more rpm.

If a car can rev higher, you can run a steeper gear allowing better acceleration. Also, at higher rpm, while the other guy is shifting, your at peak power. A bored out tpi is about the best steet-intake I know of. Gobs of torque with a mild gear and decent hp and rev band. Not ideal for racing, but it can hold it's own. It makes me angry when people ditch it for an LT1 or Something like that.

 

Yeah For some reason I'm very happy with my 2.59 gear ratio with my TPI and my mild mods. It's a monster it'll smoke tires if i want it to or i can slowly eaz into it and have a great pull with no tire spin until I shift. my shift points are at 1st to 2nd gear 43 mph and 2nd to third 83mph. Blower is next( one day). anyway thats my two cents about it, it's about what you want, you might not even wanta waste your time and just slap a LT1 intake? I'd do a lot more reseach first about what you want... but if you do the port job just be ready for it taking time outta your day.

 

On my old combination I ran a comp xe264hr cam with a fully ported :Plenum, base, runners, L98 iron heads (no siamesing of the runners or base)

I did alot of homework on how to home port, and took my time using the standard abrasives porting kit, and air tools, and an egg shaped bit for the aluminum.

and I have to say it made a very noticeable difference in how the car reved. it reved quicker, pulled higher, and ran much smoother.


When I ever need to pull the heads/ intake on my new set up I will do the same. a guess would be up to 30 more fwhp. Very worth it for a free mod, just if you're not mechanically inclined, or don't have a firm concept of what your intending to do , don't do it.

there are many opportunities to screw things up, if you do radical things, and don't finnish them out correctly, many have lost power from siamesing becuase they either took out too much material, or really didn't know what they were doing.

Can be rewarding if done right... even on a stock set up

 

Note on my end no siamesing of the runners, base or pleuim and i got very good results same as Kennerz