1989GTATransAm

iTrader: (3)

"1.9" should flow quite well."

Yes it will assuming you are talking ID. BadSS has worked with the First quite a bit but not siamesing the runners. He was looking into it but I don't think he ever did.

I think Vincent is correct in only leaving from 1/2" to 1" of divider wall in the runners. That is all I have left in my SLP runners that I mated to the First intake manifold and that thing really revs up with the old motor making peak horsepower at 6500 rpm. By the way the ID of my runners at the base manifold inlet is 1.85". When I was measuring things it looked like one could go to 2.00" ID looking at the intake manifold port.

ASE doc

I plan to install the FIRST system on my motor this winter. I am going to see if I can port and polish it to 2" to begin with and leave the runners full length. I expect to see a significant increase in top end and peak power/rpm just from 2" smooth runners. In the future, I may siamese the runners for increased power. I have plans to eventually build a 600+hp 373. Ive thought that I would go with something like the Mini Ram or a custom tuned runner intake. Now I'm thinking that with the right mods the FIRST system may support 600hp just fine.

I shift my current set up at 6,000 and can run it to 6,800. However, I do admittedly see a drop in acceleration above 6,000. For anyone else considering it, the ZZX runs very well with my high flow, full length TPI system and is actually very drivable. It makes noticably more power than the 224/230@050 503/512 cam that I started with.

cuisinartvette

Id fall over to see someone make 600hp 350/383 with a first. They have cfm but to make that power you need some RPM wondering if sheer runner length would kill that dream, hard to make that on a typical single plane and drive it on the street. Would be fun to see someone try thouhg.

1989GTATransAm

iTrader: (3)

You are not alone in the thought of making 600hp with a TPI system. After Bryce/Dr J got the Accel to over 330 cfm people started getting ideas.
Bryce was very surprised that the manifold would flow that much.

With the First base I don't know what the CFM limit is. The problem area with the First system is the runners. If one was to weld them up and then eliminate the divider(siamese) except say for the last inch then that area would become an extension of the plenum and cut down on the runner length and increase airflow. We have already proven that with our siamesed SLP runners.

When I was measuring mine(First) it looked like one could open the intake manifold entrance to 2" in diameter. It would be no problem to open the head side to a Felpro 1206 gasket. That would support some serious horsepower.

If using a 350 you would have to wind it to the moon with a solid roller. It would be a much easier path to use a 400 or so cubic inch motor and maybe a hydraulic roller with light weight valve train parts.

If one was to use the Accel base, then a welded and siamesed runner set would do it. A monoblade throttle body would have to be used but that is no problem as I am running one now. I think it is very doable. It only takes time and money.

86 camaro kid

I have a quick question. I've been searching for a cold air intake for my 86 tpi but i can't seem to find anything. What would be the best way to fabricate one of my own. im not looking for any major hp gain maybe 10-15 or so.

1989GTATransAm

iTrader: (3)

For a Camaro I would think reworking the stock one. The bottle neck is in front of your MAF where the round part transitions to the flat. There are a couple of threads on the subject with one member offering to do the work for a price.

On the Firebirds we have been using 3.5" aluminum tubing to make our cold air intakes. The bends are readily available with an internet search.

skinny z

https://www.thirdgen.org/forums/tpi/...pi-camaro.html

articwhiteZ

iTrader: (56)

just need the right parts. to make the HP and TQ. your looking for is all. Lingenfelter did it back in the 90s. even had a all 50 state smog tpi makin 500+HP stage 5 eng.

1989GTATransAm

iTrader: (3)

"Lingenfelter did it back in the 90s. even had a all 50 state smog tpi makin 500+HP stage 5 eng."

With the advances in head and camshaft technology it would be easier to duplicate in todays world.

Americanmouse

iTrader: (7)

I had my stock TPI intake and Maf stolen from me a few years ago. So I searched around and found a cold air induction that SLP makes. I also purchased a Granatelli Maf. my current setup works very well now, although I did have to move my battery.

3rdgenred

iTrader: (1)

What do you guys think, numbers wise, someone would get if they ported thier whole top end. Stock base, ASM, and plenum to all match, but left the same heads? It would bottle neck but some HP gain right?

cuisinartvette

Youd have a gain but yes heads a bottleneck.

Id guess the airspeed takes a huge nosedive in the runner area as compared to in the plenum. Not hip to all the harmonic wave tuning but it would seem to me a potential problem area somewhere in the curve

Will be taking on a FIRST project soon, will post up how that one goes.

Nice to see some serious butchering going on love it lol

BuzzLOL

[ What do you guys think, numbers wise, someone would get if they ported their whole top end. Stock base, ASM, and plenum to all match, but left the same heads? It would bottle neck but some HP gain right? -3rdGenRed ]

.. The stock 225 - 250 netHP TPI 350" setup makes about 300 - 320 no air cleaner/open header gross flywheel HP... the stock L98 heads die at about 375 - 390 HP... so improving the TPI system can gain the difference between those numbers... say about 70 HP... above that, something needs to be done about the heads...

.. The stock TPI 350" cam about 207/209 duration wants to make about 335 - 345 HP at 5200 RPMs... but the stock TPI setup tends to cut that off about 4500 RPMs... so a little bigger cam like a GM Hot Cam 218/228 wanting to make about 415 -435 HP would easily max out the stock heads... maybe a might smaller 214/224 roller cam would be best match for stock heads with improved TPI... along with best MPG and best low to mid RPM torque...

.. In any event, good air intake and headers and freeflowing exhaust system is a good start before any of the above... can recover 20 - 60 HP lost in whatever your stock exhaust system is... if you start this build, you should start your own build thread to discuss it, because these guys are on a whole different level looking for 500 - 600 HP... but they will drop into your thread to help you out... look through the other thread titles and make up a thread title that says what you're doing like Improving TPI w/ Stock Heads and doesn't sound like everyone elses so we can keep track of you... you might even cut and paste these comments pertaining to you into the beginning of your thread...

Tonysz383

Don't spend any time trying to make power with the stock base plate. They are the cause of most rectriction in a stock TPI. If you want to replace anything in a TPI intake start by replacing the base plate with an Edelbrock, TPIS or Accel unit. Then if you have more money replace the runners and then the TB.

Dark Ember

I thought the title of this topic was apropriate for this post. I recently ported out the stock TPI, on a mostly stock L98. I siamesed the SLP runners to look more like ASM runners than SLP's. I gained .1 et, and 2mph in the 1/4 mile. I don't doubt that on a more modified engine, it would have been better.

https://www.thirdgen.org/forums/tpi/...rs-ported.html

dfarr67

iTrader: (2)

Edelbrock I suppose clean sheeted the manifold for the convential head- with their engineering resources- why did they not make a manifold more comparible to what is seen here (within reason), would have been more cost effective casting rather than a million hours porting and welding. Not like there is many choices out there for vortec bases anyway. i used to think their products were pretty solid, but with what I read- too many short cuts, especially with the current competition out there. Running on name can cut both ways.

oramac91

iTrader: (5)

So is open the plem and runner wide open the thing to do?

oramac91

iTrader: (5)

You make them out of scrap?

cuisinartvette

Responded to you link. Lots more on the table for you.

PhoenixFirebird

iTrader: (2)

Have any of you guys experimented with a siamesed base? When I bought my SLP runners and Edelbrock base from the TGO classifieds, I though I bought ported components. I didn't pay enough attention to detail to realize the lower runner ports and upper intake manifold ports were siamesed. Not really what I was looking for since I'm after the "fun monster torque car," but hey, I don't mind spinning this motor to 6k if that's where it makes power.

Just curious to see if any of you have really dived into this next step. So far all I've really seen is from the vette guys, and from what I see, they're making some decent gains from it.

Pics from the seller:

Dyno Don

iTrader: (7)

How is this for a torque monster, with the modded short SLP runners.
That's over 420 @ 3500 and 430 peak and still 400 @ 5000 to the rear wheels.

355 cu. in.

actarnoff

iTrader: (1)

What are the specs on this bad boy?

1990IROCZmw

Looking for a factory ecm chip for a 1990 iroc. ATNW is what should be on the chip. It's a 5.0 5-speed. Any help would be appreciated.

TTOP350

iTrader: (8)

Perhaps post in the correct forum? parts Wanted is good place to start.

Dyno Don

iTrader: (7)

My combo....
Stock block .030, stock crank, ZZ4 rods, AFR 195's (1040's) 10.7-1 comp.(TRW 2 reliefs flat top pistons)
.038 quench, custom Jones cam (228/228 .565 113LSA, 1 3/4" shorty headers, 3" cat back system, intake that flows 300+ CFM, 3.73's, 3800#
with driver, idles at 750 RPM's runs on 87 around town, gets 25+ MPG on the HWY, peak torque @ 4900, peak HP @ 5800 and passes the Ca. smog test.
400/430 to the wheels

wulff

It's been awhile since I posted here and since I am a 4th Gen Monte Carlo SS owner I always feel like the red-haired stepchild.
What I was wondering, since we all love the looks of a TPI but want them to flow to 6000+ and STILL make horsepower, I don't have any current 1/4 mile times but some years ago one of the magazines built a 'torque' motor and shifted at the peak torque. If I remember it turned some good times. I know 'off the line' my 406 with modified TPI will pretty much leave all imports at the intersection!
What I am wondering, has anyone done any high HP vs BIG TQ numbers on a 1/4 mile? I guess it boils down to what you want, I wanted a motor that was very street-able yet had a sickening amount of torque to get it moving in a hurry.
I am running a T-56 and 3:73 rear.

Imadude_134

iTrader: (9)

Probably from ignorance im asking this, but would there be any additional gains by going longer stroke or wider bore? What are the benefits to stopping at a 355 instead of going larger?

Dyno Don

iTrader: (7)

Even with the large high flowing (welded) intake we do, it's still maxed out at 355.
Any larger cubes and you can't get enough air into the cylinders.

TTOP350

iTrader: (8)

Hate to bring up a old thread but has anyone ever tested SLPs 1st batch of runners vs. the newer stuff?
One set of runners (my hand is on them) on each side of the motor doesn't have a divider and the other pair has one. They used to say, "helps make 2 distinct tq peaks". These are stock with 0 port work and look like a 5th grade shop class made them.

1989GTATransAm

iTrader: (3)

I had them on my builds. I consider them better than the second design. IMHO they flow a lot better. In fact those are the ones I used when I mated the SLP runners to the First intake manifold. I like them.

B4CHawk

I'll have a bit to add to this thread. In January I'll be pulling off my intake and sending it off to Bryce/Dr. Jay for welding and porting, and I'll also be handing off my plenum to Dyno Don so he can port the TB to accept a 52mm TB. After that the plenum will be sent to Extrude Hone.

This is what I'm running as is

355ci, comp 305 cam (220/230, 114lsa) Sportsman II heads ported and polished (unknown flow), Edlebrock base, GM plenum (both port matched), AS&M runners, 48mm TB

This is the first baseline dyno; it was running a bit rich, with more tuning I'm sure it would have it 300whp. I'll add my results when I put it back together.

TxTtopZ

Yeah, old thread for sure.. but still a good one. The only thing I can gather from the whole "ordeal" on why the numbers fall off is because of it's unique layout. If I may start up a debate for the sake of science here..on the subject of reversion... Siamesed runners tend to "add" plenum volume by actually increasing the runner size to a point that air velocity slows and is now "drawn" from the modified area. This in turn makes me believe that "golden" second harmonic is not only lost from velocity change (2 different sources of plenum area changing the speed twice, in 2 different directions at that) but now the air from the "needy" valve is pulsed THROUGH another harmonic wave from the shared runner "brother valve" - and possibly shattering the "charge". (Picture someone throwing a watermelon at you but you cut it in half thus having 2 pieces go by either side of you. (You have just became a runner divider wall in a siamesed TPI runner) One valve harmonic is now "trimmed" and heading down an un-needed path and probably wasted, THEN reflected at possibly the time when it needed it to go the other direction - or some other variance of reversion.

Still with me?

Lets look at the modified intakes in this post. You have one 5"-5.5" singular port (cylinder head intake port ) literally running through it's own individual base intake port (like other intakes) which BRANCHES OFF into a dual shared port which it can not only draw off, but actually REFLECT harmonics into. Then you have another plenum area with it's own entirely different "environment". I seriously cannot think of any other intake layouts like this... As far as direction, speed and pulse waves go - it looks like it would be a madhouse with air traffic constantly running into each other.... Not only that but you are still left with the "tuned" runner effect, just more area of it. From what I have seen on the FFI intakes, this remains truth even in a completely redesigned system that still mimics the factory pieces.

I stand by the main plenum being separated by "X" amount of runner (no matter how fat you've made them) being the culprit on the issue. If you just cut the siamesed portion off and created a "Tuned Port Tunnel Ram" so to speak, the RPM potential would be higher.
Any ideas or info out there?

Dyno Don

iTrader: (7)

Here is some of the difference it makes:





Doing this to the runners:

BuzzLOL

. I think the harmonics dissipate when they get back up to the siamesed area... the new shorter tuned runner below the newly siamesed area tunes for higher RPMs...

. Personally, I prefer to mount the EFI plenum on top of a Weiand HiRam tunnel ram base...

. Nice charts Dyno Don... anything to keep the torque from diving so hard after 4700 R's...

TxTtopZ

Is that dyno graph a back to back pull with no change other than those runners?

86redIROC

Good question..........

Dyno Don

iTrader: (7)

No, that's two different combos
One auto the other manual.

TxTtopZ

I still would like to see a conventional intake with a tune for a comparison. I know your not a magazine but at least we would have some piece of mind of what we're leaving on the table. Somewhere to "push" so to speak.

The curves cross at a good RPM - are those graphs from you and your son's vehicles? Im trying to get my head around the combinations used.

Anyway, wonder how that intake would fare on a 305 with a smaller bore.

Dyno Don

iTrader: (7)

One is mine the other a club member ......the one below is also a club member.
Here is a different combo.
350/ported 113 heads/LT4 hotcam/edelbrock long runners/ all parts extrude honed/1 3/4" shortys/
auto trans/3" catback Magnaflow:

Notice the downhill slide after 5K

BuzzLOL

. If HP and torque scales are the same, HP and torque curves on a graph ALWAYS "cross" at 5250 RPMs... that's from the math formula that computes HP from direct torque and RPM measurements... HP is a calculation, not measured directly...

. On the last graph, note how HP peaks at 300 and continues flat at 300 as RPMs increase, can't go any higher, until finally starting to fall off... that flat top on the TPI HP curve is what we try to cure... or at least raise the flat top higher... and slow the torque fall off as RPMs increase... get that 5250 RPMs 'cross' up at a much higher level... like in the previous two charts...

. That GM 'hot cam' used in the last graph engine would HP peak at 5800 - 6000 RPMs in a carb.'d engine, but the TPI has the HP peaking way down at 4250 RPMs... and it can't get any higher HP... although that cam/setup allows it to keep revving and just making more noise only... the too long intake tract of the TPI setup does that on hotter/bigger engines... it's tuned for lower RPM torque...

. TPI was apparently designed for a 305" engine and works best on one... with a good power curve and higher RPMs... on 350" and bigger engines, you get that stunted flat topped HP curve...

. Of course, 300 RW HP is great on a modified '80's street car... even the 1960's 'muscle cars' typically only had 225 - 275 RW HP in stock configuration...

TxTtopZ

Im aware of that... Long day at work = brainfart.
The reason I am interested is because my car has a T5 - so I am basically trying to come to the conclusion that a warmed over 305 would have a healthier looking curve (to an extent) than whats showed here and be more "apt" with TPI. all though, I'm probably just better off with a SR and call it a day.

BuzzLOL

. A budget SR can be created by putting your TPI plenum, injectors, and all other EFI parts onto a Weiand HighRam base... and that base prolly work better than the SR setup...

cuisinartvette

420tq to the ground out of a mild cammed 350 is super impressive those arebig block #s

First stock base I ever ported was on my 89 Vette about 10 yrs ago
Similar gains as yourself think I got 1mph have to dig up timeslips


On the stock base being a waste it depends, if youre talented and patient you can get some air out of them.

Finished one last week that went 238cfm on the first pass. Made a fewminor tweaks, itson the bench again right now.That was also done on the "slow" cyl with a lousy clay radiused entry. Should go better than an edelbrock when I get it back. Not bad for free! To pay someone for it, not worth it.

1bad91Z

iTrader: (1)

I have a high-flow TPI lid with connecting tube available if anyone is interested. This is one I built awhile back for one of my personal cars that I sold. I will not be building anymore due to material cost and lack of free time. PM me if you are interested!

cuisinartvette

You can get some power out of a stock ported base but its going to take some doing..meaning lots

Just finished one and using a radiused clay entry got an honest 244 cfm out of one wasnt much left of the casting though. many many hrs in it.

Still think there may be more or hoping
At the base of the runner entry the flange almost appears like it could hamper some air in there well see
Going to get a velocity stack and mate it to a wooden fixture I made see if it picks up anything or wasted even more money on one of these pos LOL

Get your hands on TPI stuff esp aftermarket basesnow if thats what you want. They arent going to be made much longer trust me once they are gone they are gone forever.

If you have to have 300 or close to it out of a base just go get a first dont waste your time trying with the smaller stuff

355tpipickup

iTrader: (5)

Subbed

Third Gen Will

iTrader: (1)

Try a company called TPIS they clam it makes power up to 7500 rpm.

UltrSSKen

your cam might be the limiting factor, it makes all its got before your desired peaks

Dyno Don

iTrader: (7)

We finally found the answer to the falloff @ RPM's.
There is something in the 305 manual prom that we cannot address using RT tuner. We have been using the 305 program and modifying it to work with a 350.

We now use the Corvette manual 350 program that will allow the RPM's way past 6500. That program is used in the Corvette ECM that has the same printed circuit board as a '7730.

HTH

no new tires

Where's the new chart, time to pony up.