So I am thinking of taking my stock tpi with headers and 3" exhaust and making the intake flow better. My question is am I waisting my time if i dont do anything with the heads? Id love to change the heads but my bidget dont allow it.


Here is what i was planning for the intake.


52mm throttle body

SLP runners

Sending my intake to this place to have the plenum ported http://arkansaspolishing.com/porting.php#3

maybe change the base - but man thats expensive - would love input on that too


but in doing all of that am i waisting my time and money if i leave the stock heads? also am i accomplishing anything by doing the runner throttle body and porting the plenum if i use the stock base?

also are these changes that will require tuning?

Thanks

 

Just about anything you do will help. The base has a pretty restrictive sizing where the tubes connect IMO. They taper down porting that area and gasket matching everything will help.

 

I would save my money up and do it right put a set of heads so it can flow.

And if if have tore down that far mite as will put a hotter cam in it not that much more work invoded and cost not that much more either you have to put new gaskets and fuilds in it anyways.

You dont have to go full race cam even a very mild cam so it can breath.

Let the motor Breath Dont open everything else up to breath just have something else chock the flow and waste your money and time.

Roller motor you can reuse the liffters and push rods if you go with a aftermarket push rods guilds you have to get new harden push rods anyways.

If you have a Falt tappet motor you can pick a cam kit with liffters for $140.00.
Same for push rods.

Timming chains are cheep like you have it torn down that far mite as well do it right.

Plus the other stuff your planning to do.

You most likley have to havs a chip burned anyways so might as do all at once.

Hate to have you put all the money and time in to it and not be happy with it.

 

When I put a new 355 mild built motor into my car it was OK but something just was not the right combo it would run but I though it should had more *** behind it.

The 355 had the heads cam injectors ect so It should ran alot harder than it did.

1st it was the convetor did not have enough stall the trans place told me it was a 2200 stall after pulling the trans it was a 1600 stall that killed the car also the 355 ate it self from the inside out due to the company that rebuilt the short block anouther story.

Now I have a 383 all the right stall and the right combo I could not more happy with it.

If you dont have the right comb that will work together just not feel and run the way it should.

 

Like a lot of us, you can't afford to do everything right away. That's fine, and it makes sense, just keep in mind that you won't see the real benefit UNTIL you do the heads. ....but, once you DO swap heads later on down the road, you'll get more out of it since the intake breathes better.

...if you're not sure if you'll ever get around to doing heads, then no, I wouldn't bother with the intake. That being said, A good rear gear swap and a torque converter will make the stock motor a TON more fun to drive! FAR more fun than an intake.

 

slp runners, headers, 3 " exhaust, mild cam, 3.73's, higher stall t/c....think that gets me in the mid 13's?

 

Intake runner work and ported base work will yeild significant gains even on stock heads.

If you added siamesed SLP runners and ported that base out the best you could, it will run mid 13's with those mods easily.

My L98 went from 13.63 with stock TPI to 13.2-13.3's in similar air when I swapped to stealth ram. With few more bolt ons, in great air, it went 12.95. Bigger base TPI and slp runners will do the same thing

My friends 88 bird went 13.59 at 99 on stock converter, 3.70 gears, with a corvette L98 that had full aftermarket TPI and SLP runners. The intake mods help alot even on stock heads

 

I agree. I tricked out a number of these cars back in the late 80s and early 90s. It was not uncommon for the 350 cars with 3.23s to run in the 13.60 range with slicks in cool temps,,, with little more than "free" mods - ported plenum, AFPR, bumped timing, gutted air box, "ram air" w/K&N, 160* stat, adjusting the lifters to 1/4 turn, and gutted cat. That was with an untouched base and runners with stock exhaust manifolds, stock cam, and no "chip".

Most of these cars were practicaly new and plus, at that time I didn't think it would be worth someone paying me to pull the intake and port it. However, after really looking at the runners withing the base, there's no question there was and is enough potential gains from porting that it should be automatic if it is off the car and you can do the porting yourself.

When it comes around to paying someone to port the plenum, SLP runners, and base,, it adds up quick and can get VERY expensive depending on the amount of work needed/wanted. Considering you really don't need to get crazy with the porting,,, you might want to consider investing in a 6" shank large aluminum burr and a 1.5" sanding roll and doing it yourself. Just being conservative and following the normal flow of things will do just fine for stock heads - actually just gasket matching, removing the lip in the base, smoothing out the casting,, and knocking out the air dam in the plenum will do wonders. If you don't want to do the porting yourself, I'd suggest you find someone that's done a few of these and willing to port everything at a package rate.

 

good to know. thanks. i was real torn on what to do. didnt want to waist money on all the intake work for nothing. i figure with 3.73's headers and 3"exhaust and opening up the intake at least i would let the motor breath from the heads down as much as it can.


will i need a tune if i do this?

 

IMO, your 273 gears are totally relevant to the stock intake. They keep you in the powerband longer. Now, that would not be a good gear for a holley stealth ram (short runner setup). You may run faster at the track, but i wouldn't want a stealth ram and 273 gears on the street. The SLP runners would be an OK upgrade i think, wouldn't hurt low end torque too much. I personally wouldn't touch the base until you have a better gear. 342 gears are supposed to be pretty descent with the TPI and an Auto trans.

 

im doing 3.73 gears in the rear at the same time i swap in the L98 with the intake work.

 

with the 700r4, its already like having a 373 gear cause of the 3.06 first gear ratio in the trans. My car has trouble launching even with the 273

 

what intake work are you doing? porting? bigger runners?

 

porting the plenum, slp runners, and quite possibly edelbrock tpi base and 52mm throttle body


thats what i was thinking. spend the money on that stuff and leave the stock heads...


also some type of a cam, headers and 3" exhaust.

already have bilsteins in back, kyb in front and added sub frame connectors on. its a convertible so figured that was a must

 

Here's what i would do if i had the cash

Lingenfelter 219 cam (211/219 @50)
AFR 195 L98 heads
Holley stealth ram intake
TH 350 trans
373 gear
chip tuned around the mods

that is a 12 second monster

 

I wouldn't waste your money on the throttle body. Supposedly our TB's are enough to feed a 350 hp plus motor.

 

good to know, maybe just a airfoil then

 

most cost effective way would be to go and get a set of Vortec heads $600 /pair new or look at a junkyard Then add the Scoggin Dickey lower TPI base for vortec heads. Then a cam with a bit better duration than your stock. That would run you less than $1000, especially if you got the heads used. That is a 300 + hp on a tpi car.

 

Your not wasting your time at all, the results will be more than obvious. Just be sure to up your fuel pressure some if you don't know how to burn your own proms....

There are plenty of local shops that can handle the intake porting. Not sure which engine your running, but if it's a 305 then stick with the stock throttle body....

 

what year cars or trucks are the vortec heads on?

 

id say do it and mod away

i have all this on modded unported stock heads and its a HUGE increase even on stock heads

355 vortec block
FIRST TPI
gm hotcam (218/228)
Built 700r4
2200 stall
3.42 gears
all tuned

feels like a different car for sure.... i know im just a head swap away from big power....
and when i can get 1500 for heads the stockers are coming off...

 

Summit racing carries Vortec heads too

 

I believe the Gm trucks from 96' and up. Vortec motors

 

Vortecs actually outflow some aftermarket heads.

 

i should have gotten the FIRST with the vortec head pattern and gotten vortec heads considering they are very cheap compared to aftermarket heads and call it the day.... oh well.... gotta spend big money now for decent heads...

 

The base IS the restriction. changing that first with matching runners will make substantial gains in the 1/4. 2.77's/2.73 gears arent bad with the 700r4 due to the 3.06 first gear, but they still are to low for a TPI. TPI loves 3.27/3.23's minimal and work well up to 3.73's with siamesed runners. I ran 2.77's, 3.27's, and 3.42's on my TPI car and 3.42's gave me the best performance, although there was not much gained between 3.27 to 3.42. There was a big seat of the pants gain with 3.27's over 2.77's however, and it showed at the track. Picked up 2-3 mph depending on the air that day over the 2.77's.

 

I was thinking 3.73's. any downside to that?

 

Its alittle steep for a conventional long tube motor on stock cam but with a 26-27" tire at the strip they work out fine. On the street they are fun. My old friend ran 3.70's in his 9 bolt rear, full bolt on TPI L98 vette motor in a 88 bird. That car ran hard! Just about shifted into 4th gear at the end of the 1/4 mile. Sometimes he would, so its alittle too deep but that car ran 13.59 at 99.x mph on street tires and stock stall speed. 1.90 or so 60 foot I think it was. Thats pretty impressive for a stock stall/street tire car. With 2800 stall and slicks, I'd bet he'd go 13.2's, just like my stealth ram swapped car did.

My stock TPI, exhaust modded car ran 13.63 in good air, mostly 13.8's in hot weather. That was with headers/catback/2800 stall and 3.42 gears on ET streets. My buddy's car would catch me at about the 1/8 mile and slowly creep by me at the stripe. His was doing 13.6-13.7s in warm air to my 13.8's. Good race. Once I went stealth ram, it was all over. My car on slicks just got out ahead too far and he couldnt catch up.

So 3.73's will work ok. If you matched the converter to the gear, you'll likely have high 1.6 60 foots, as i was able to get 1.70's with stock TPI with 3.42/2800 combo. With the stealth ram, the higher average power I was able to get quicker 60's, I ran 1.70-1.71's. With more gear I bet it had a high 1.6. Thats moving for a bolt on car!!

 

so will the 3.73's make the car shift later? will it do that at reagular around the town driving or just at wide open throttle?

 

Gears wont change the shift rpm, thats controlled by the governor in the trans and partially by the TV cable setting. TPI that makes peak by 4500 rpm generally wants to be shifted quickly after, say 4600-4700 due to power falling off like a rock. My trans shifted at 5000 by itself so I left it there.
What happens in the 1/4 mile, depending on the mods, tire size, and converter, you can top out 3rd gear and the trans will want to shift into OD if your trans is setup for that.

My friends car trapped 99-100 mph depending on the air. With 25.7" street tire, 3.70 gears, thats 4791 rpm assuming no converter slip. If it was locked then it stays 4791, but if the converter is open it has some slip so it could be as high as 5100 or more. If his trans shifted at 5K like mine, then he would just be going into 4th gear right at the 1/4 mile stripe. Sometimes he did, sometimes he didnt.

For 1/4 mile stuff you want gearing to allow your motor to cross at peak hp rpm or slightly after. 3.70's will do that with a good TPI setup.

Now with a miniram or stealth ram, peak hp moves from mid 4000's up to 5100 or so and falls off after 5300 pretty bad so shift by 5400 or so. 3.73's in that case work well with stealth ram/miniram because you will be trapping closer to 101-102 mph That will put you in the 5100-5300 range at the 1/4 mile