dhirocz

iTrader: (2)

Wondering if anyone has considered using the FIRST base and runners and modifying a stock plenum to fit? I've been pondering the idea and using a 58mm throttle body. I would make some plugs and weld them into the factory runner holes, build weld where necessary then remachine the surfaces that mate to the tops of the runners. While I was at it, I would build some weld to the left and right sides of the plenum behind the throttle body and hog out that plenum with a carbide bit on a 6" shank... then line everything up and start drilling and cutting. I imagine it would work as well. I'm seriously considering doing this, I will probably call FIRST on friday to see how much the base/runners/gaskets are. This thread has motivated me

I never noticed if the FIRST runners have some type of cold start passages in them... either way, I would most likely block off the passages on the plenum and run IAC air directly into the plenum and not the runners.

I postponed building a 408ci TPI torque motor because I wasnt satisfied that I found a setup that met my needs. I think one of these extrude honed would be more than adequate, and with a stock plenum (sandblasted to cover the welding/machining) it would look near stock too.

I understand why you did it that way though...and it looks good! I wanna see some dyno charts

kowboy59

iTrader: (8)

Did i miss it somewhere? But if I were to buy a Fast lower intake and buy some SPL runners am I gonna have to do that adapter plate and all?

1989GTATransAm

iTrader: (3)

Kowboy59. I assume you mean First lower intake. That is the method I used to adapt the SLP runners to the First Injection TPI intake manifold. There may be other ways to do it with some imagination. The pictures in post #9 show the gaps that have to be filled. So yes something needs to be done.

To dhirocz. There has been talk about it. I'm not sure it would be feasable. The First intake runners are quite abit wider at the top than the stockers. I think your would be better off with the whole setup from First. With a little work it can be made to look like a stocker.

Also you want to look at your goals for the motor. Like how long should your runners be for the rpm range of your motor? What is the cross sectional area of the pushrod pinch area in the heads you will be using? What is the best average CSA and taper for your application? Things to think about and research.

IMHO the runners on the First Injection TPI intake are too long as they come from the factory for most performance applications. Probably fine for a close to stock motor. However they can be shortened by the siamese method as BadSS is working on.

One more thing what I have done is not for the feint of heart. A whole lot of work went into this. I would assume for most people that don't have a lot of time or easy access to some machine shop work this would not be a way to go.

Here are three options available for a improved TPI intake system.

1. Buy a complete First Injection TPI intake system and modify it if need be.
2. Buy the Edelbrock TPI manifold and SLP runners and modify both of them.
3. Wait and see what BBK comes up with. They have a good opportunity.

dhirocz

iTrader: (2)

Well I have access to alot of the tools I would need to get the job done. The welding I can do myself, and I have friends who can mill the intake to where it would need to be.

I would eventually semi siamese the runners, though probably not much. That would be the last thing I would worry about.

I want to keep the stock plenum though. The whole setup looks very close to the factory TPI setup, but the plenum doesnt do it for me. Given i would be completely modifying it... which doesnt concern me. i know I would have to do quit a bit of porting and welding and relocating of the holes to mount the runners to. I want to keep the stock accelerator cable bracket, the stock throttle body, look of the stock plenum, etc... Basically make it more of a drop in to a TPI car than a one off needing specific parts, if that makes sense.

I have also been considering going monoblade, but I still think it would be overkill for a 4" stroke TPI engine. This would be a torque engine, something also daily driveable. Any siamesing would be minimal.

Something else I would do would be to take my short aluminum plenum extension (for coil in cap distributors) and weld it onto the plenum before sandblasting and grind it all nice and pretty for more of a smooth look. The plenum would also have the sides behind the TB built up for porting a little bit...but I think I could do a good job to disguise the modifications and have a really good flowing near stock appearing TPI setup. The idea here is 'sleeper'...meaning stock valve covers, stock appearing intake, stock type damper, no lope, etc...

1989GTATransAm

iTrader: (3)

Here is a picture of the stock plenum next to the First plenum that I downloaded from BadSS post on the subject. It will let you know what you are getting into.

Take a close look at the alignment of the intake holes between the two plenums. Also what is not shown is the difference in the width if any. Not saying it can't be done but it will be a lot of work.

dhirocz

iTrader: (2)

Very true. Anything can be done with metal though I am also aware that the angle is different. I think that will be the hardest part of the whole plenum modification, but with a good plan, should be easily manageable.

Thanks for the pic!

1989GTATransAm

iTrader: (3)

Aluminum is fairly easy to work with. I have some ideas on how I would approach it but would need the parts in hand for confirmation. One of the problems will be how to hold the plenum while machining it. You will most likely have to make some type of fixture/jig to hold it at the proper angle. However if you also modify the attaching plates on the runners you can make your own angle.

dhirocz

iTrader: (2)

On question I have though... what kind of welding rod did you find that worked best on those intake manifolds? I have some aluminum rod but some is for different alloys, and welding intakes is not something you do everyday...

I have some 1/8" 6061. I also have some wire, but I really wouldnt use that unless I was siamesing a stock set of runners or something. I also have some 4043 but it's pretty thin rod.

Most of what you find nowadays is that aluminum brazing rod that you see... not the same thing!!!

1989GTATransAm

iTrader: (3)

I did not do the welding. I had a local shop do it for me. He was interested in the project so the price was vary fair.

1989GTATransAm

iTrader: (3)

We had out bimonthly SoCal Third Gen meeting last night. InsaneIroc brought over his complete First Injection TPI system. I wanted to measure the width between the First and the factory plenums.

The factory plenum tapers and the First plenum is straight on the sides. The factory plenum is wider at the top and narrower at the bottom. So in the middle they are the same width. So with a "lot of work" it is not out of the question to be able to make the factory plenum fit the First Injection runners.

dhirocz

iTrader: (2)

sounds easy enough then. I guess I'll have to start my TPI project too I'll get a measurement on the width between the runner flanges with them installed with some space for gasket thickness, compare the distance top to bottom to make sure it is the same, build some weld, then have the sides of a factory plenum milled to spec after welding the runner tube holes shut. Then do some cutting, drilling and tapping to mate up to the new runners

I love the odd and custom stuff lol gives a project some one-off personal flair... keeps it from being 'just another bolt-on car'

355tpipickup

iTrader: (5)

cant wait to see more on this thread!! great work! making more HP from the top end of the tpi is just what we need....keep up the great work!

1989GTATransAm

iTrader: (3)

"build some weld"

I think there will be a whole lot of that going on. You will have to completely redo the sides of the factory plenum.

Guest

Whats your thoughts on it though? I cant see how modifying the FIRST runners to fit the factory plenum is a whole lot different than what you did, other than that the FIRST runners dwarf the factory plenum. Just cut them and weld on some adapters to a factory sizing and bolt pattern, blend them in, and done deal.

Whats your 2 cents?

1989GTATransAm

iTrader: (3)

"Just cut them and weld on some adapters to a factory sizing and bolt pattern, blend them in, and done deal."

I'm not sure you can do that. Look again at the picture in post 55 and how the holes line up between the two plenums. He would be going from large holes and spacing(First) to smaller holes and spacing(GM). On mine I went from smaller holes and spacing to larger holes and spacing. Also on mine the edge of the first hole in each SLP runner pair pretty well lined up including the left bolt hole for the pair. That made things much easier and that is one of the main reasons I thought it was feasable.

On what he is doing I don't see much of anything that lines up. I have had a couple of thoughts on how I would approach the problem he is facing. One is to completely cut out the sides of the plenum at least where the runners are attached and weld in say a new 1/4" aluminum plate and blend it in. That way you would have a clean surface with no holes and you can start from scratch. You could also weld it in vertically to match the angle of the First runners.

The other way would be to weld up the surface area on the sides of the factory plenum and then machine it to the dimensions. I both cases I think the flange on the First runners will need some work done to them.

If BadSS is reading this post maybe he can chime in. He has both intakes systems at hand. It might be posible for him to do a mock up like he did for me. In this case he would use the First intake, First runners and factory plenum. Then post some pictures.

Guest

I guess I should have grabbed one of the plenums and set it on top of the First sitting there and taken a look.

Honestly the lineup doesnt look all that bad to me. I'd be more concerned with the right to left rather than the misalignment on the side there. Slide the plenum forward slightly and cut open the entire side to fit. I'd be more concerned about how the driver side lines up especially those back pair of runners.

1989GTATransAm

iTrader: (3)

I agree that is possible. The back of the factory plenum on the drivers side can be extended if need be. Just more fab work.

He might want to make his own flanges on the runners. Right now they are separate pairs. Maybe make them one piece like on the factory units.

1989GTATransAm

iTrader: (3)

Couple of delays in finishing the project. As stated above my machinist has been in Mexico for two weeks. He got back and has to house some relatives because of the fire evacuations here in SoCal. Next week we are doing a kitchen remodel.

So maybe the 2nd week in November before the project starts back up. I'm so close to the finish line.

dhirocz

iTrader: (2)

It'll be a little while until I can get anything done either. I am in the middle of moving and I have to take a trip next week. Then I will be spending some cash on some stuff for my place like a washer and dryer...so it will be a little while.

as soon as I can I am going to start this. I have a 1990 plenum I may use, the plan of attack really depends on what I see when I get to play with the setup for a little bit. It may be easier to weld in a new piece of metal, but I would be worried about finishing the inside of the plenum. When I port the plenum, I usually grind out all the casting for the blind bolt holes as well to help reduce turbulence. Takes more work but its worth it.

We'll see when I get to see it in person.

1989GTATransAm

iTrader: (3)

Here is the latest progress report. Manifold and everything installed. Car is up and running. Took it for a test drive. Couple of problems yet to be done.

The biggest is there is a miss and only apparently running on seven cylinders. Please let be fire. I have to let the car cool down and me rest up before I look into it. Next I need to order the correct cruise control stud as you can see in the picture the cruise control cable is not hooked up.

Last problem is I'm going to have to shave the strut tower brace as it is a little to fat to properly close the hood. I already thought this might be the case and have a plan of attack ready to go. The First intake manifold raises the runners and plenum up about a 1/2".

Also the throttle body is the AS&M monoblade. Seems to drive just fine. Hard to tell there is a First TPI Intake manifold hiding in there. I put it in and it is hard for me to tell. Hahaha. Here is a picture of the installation.

rocluvr0013

That is a beautiful thing. Keep us updated.

BadSS

If it's a dead miss, easy to determine which cylinder by doing the ole lick the fingers and lightly tap on the header pipe trick. Hopefully you'll find it before spouting seven superlatives or burning off the tips of your fingers.

Glad to see it up and running and looking great!! I don't believe you're going to be disappointed in the WOT results either!!!!

1989GTATransAm

iTrader: (3)

Yeah, I just hope it is not a clogged injector. I really don't want to take it back apart again seeing as I have no leaks. Anyways I will take it by Dyno Don's tomorrow and have him put the heat gun on the headers to see which one it is. Got to save my fingers.

Once I get the miss problem solved and everything else seems ok I will put it on the dyno and see what she does. Hopefully this week. This system will flow a lot more air than my previous setup. With any luck the increased flow will show up on the dyno.

Edit: One thing about the AS&M monoblade. It is not exactly a direct swap out so beware if you want to use smog etc. I had to have the canistor port machined, the pvc port machined and the egr port machined. On my installation with the First I had to do a 180 degree on the IAC valve in order for it to fit. Also they use the LT1 sensors. I also had to relocate the throttle cable as you might be able to tell in the picture.

Guest

I think I see the problem. The valve covers say Chevrolet, but the engine is in a Pontiac.




Maybe you didnt get all the injector connectors or spark plug wires on? Or... just for kicks... might want to make sure none of your injectors are grounding themselves out on the manifold. I've heard of that being an issue and with that creation who knows.

1989GTATransAm

iTrader: (3)

Thanks Madmax. Actually there is pretty good clearance around the injectors. The fuel injector clips are easy to get to and I double checked them. Will check the wiring one more time. I don't see a problem with the spark plug wires either. Even checked for a light show after dark and there was none.

1bad91Z

iTrader: (1)

Lookin' good!

If you dont mind, I would like to see a picture your air induction setup.

1989GTATransAm

iTrader: (3)

Check this link for my cold air intake picture. I have the air filter area blocked off from the rest of the engine compartment. It draws air from the fender well and the front headlight area. Between that and the AS&M monoblade there should be no air restrictions. The tubing is 3 1/2".

https://www.thirdgen.org/forums/tpi/...t=#post3019549

1989GTATransAm

iTrader: (3)

OK, went by Dyno Don's shop this morning. Bottom line I had cylinders 2 and 8 spark plug wires backwards. Can't believe how well it ran like that.

I have the dyno pull set up for this Saturday at 10:00am for the local guys if any one is interested. Car is running real good.

Guest

Wish my trans was ok, I'd join in.

InsaneIROC

Hey thats were my valve covers went I been looking for those.

Jproz1167

iTrader: (3)

wonder if my plenum was opened up for a as&m monoblade. do you have pictures of your plenum without the throttlebody in place?

1989GTATransAm

iTrader: (3)

Yes. Look at replies 5, 9 and 23 of this thread.

Jproz1167

iTrader: (3)

That answers my question guess a stock style throttlebody is pointless on my system since it has been cut out for a mono-blade like your plenum.

1989GTATransAm

iTrader: (3)

A stock style throttle body will work just fine. You can use a 48mm, 52mm, 54mm, 58mm or the monoblade throttle body on your plenum. Whoever buys it will just bolt on their throttle body with no problems.

Jproz1167

iTrader: (3)

what kind of rpm's can be pulled with edelbrock base and slp runners and poted plenum?

1989GTATransAm

iTrader: (3)

Low 5000's for sure. With work on the runners and manifold up to high 5000's for peak horsepower. We have some people here locally doing just that. Will find out soon.

Zipdrive

Allen, that looks fantastic! I would like to stop by for the dyno run this sat. Where are you going to have it done at?

Cheers.

tom.

1989GTATransAm

iTrader: (3)

The dyno pull will take place at Dyno Extreme, 8260 Cerritos Ave., Stanton California 90680. Telephone 714-828-9182.

I will be there at 10:00am but I do not expect the dyno to take place until the very earliest at 10:30am but probably later like 11:00am. They are slow to get going on Saturdays. The building is on the South side of Cerritos. You will most likely see a sign saying LAutobody on the West side of the building. Dynoextreme is on the East side of the same building. Allen

Guest

Make sure Sarkis has the thing calibrated right

1989GTATransAm

iTrader: (3)

Yeah he had the tech out from Dyno Jet. Also had his equipment calibrated. Should be as acurate as can be. I want to use the same dyno this for a comparison. I will also double check this time before I post.

Guest

1989GTATransAm

iTrader: (3)

Had the dyno pull this morning. Basically I have the same problem I started with before the First intake mod. The power goes to 350RWHP at 5000 rpm and then is flat all the way to 6000 where we stopped the run.

I'm going to have to think about this. I have no idea what is going on. There is no reason that I can think of that the motor stops making anymore power at 5000rpm.


Edit: I think I'm going to have a hard look at my torque converter.

Guest

You datalogged it right? Check the MPH vs RPM.

I'm also pretty sure I heard that thing misfire in the upper RPM, the graph indicated that as well. Might want to check the ignition as well.

1989GTATransAm

iTrader: (3)

Thanks Chris. I was going over the datalogging and that is what gave me the idea of the torque converter. I have the Yank SS3600 and it looks like it flashes or extends the range to around 4900rpm. That corresponds to dyno graph.

I thank that is to high. Don has Jerry's old 2400 torque converter which will be easy to swap out to see what happens. You are right on the electrical problem in the higher rpms and I will deal with that.

I'm just wondering if there is slippage in the torque converter that only allows 350 horsepower to the rear wheels. I'm running Mobil One in the transmission. Maybe I can get a hold of Yank for their opinion. The Yank has an STR of 2.5 which may be a little high for my taste. Also transmitting to much torque early on and harder to get traction off the line. I might consider sending the torque converter back to Yank for modification. I will give them a call Monday.

1bad91Z

iTrader: (1)

I don't know if this will help, but here ya go.......

I helped a buddy of mine build his turbo mustang (1990 GT). All we had was 2 3/4 inch pipe to plumb the air from the intercooler to the bonnet on the carb. The car peaked at 640 rwhp @ 4,900 rpm's and stayed there all the way to 6,500 rpm's. We pulled the intake piping off and installed 3 inch intake piping. The car then made 762 rwhp @ 6,500 rpm's (where his cam peaks).

If your setup is speed density, try making a dyno pull with the air intake piping removed (open throttle body) and see what happens. If there is no change, then I'd place my money on the converter.

BadSS

The LTR intakes will make a converter flash higher than when a short runner system is used. Still,, 4600 is a big jump for a 3600 rated stall (since most have a hard time getting to their rating in the first place). There are probably issues there.

A few things come to mind on the flattening HP. Runner length, which you've addressed and should be peaking higher than 5000 with your cam and heads. Misfire in the ignition as indicated (and you're looking into that),,, as well as limited INTAKE flow,, which you've seemingly addressed. Valve bounce (spring pressure or lifters),, would give you an upper RPM miss and flat-line the HP. It could be the stall,,, especially if the RPMs don't match the speed. I'm not used to making this level of power running through catalytic converters,, so I'd probably swap the stall and if still flat-lining that early, I'd uncap the exhaust at the cats.

Even if this FIRST didn't give you a huge increase of power at the top end,,, with your heads and cam,,, it should be filling the cylinders easier making more power sooner than the Edelbrock set up at the least.

1989GTATransAm

iTrader: (3)

Thanks guys.

The intake consists of 3 1/2 inch tubing from a very large K&N airfilter to the AS&M monoblade. On previous tests removing the airfilter did nothing horsepower wise so I do not see a restriction there.

BadSS yes I will look into the torque converter issues. The misfire in the ignition occured around the 5700 rpm mark. I thought limited intake flow was the issue with the Edelbrock intake and why the power was stopping at 350rwhp. Those issues should be gone with the latest system. The new design is better and flows a lot more cfm.

Now valve bounce was brought up by a couple of people and is a serious contender. There is no question I have valve float at 6300rpm as you can hear it without a doubt. My intake valves are .100" longer than stock plus they are 2.05 inch versus the 2.02 stock diameter. I'm running the Comp Cams 918 beehives. I have them shimmed to around .060 to .070" of coil bind.

The exhaust side is also .100 longer but the standard 1.60" diameter. So they do weigh a little more than the standard valves. If it is valve bounce it is not obvious by looking at the dyno graph or hearing it outside of the horsepower just going flat.

The exhaust is 1 3/4 inch headers with a 3" collector necking down to 2 3/4" pipes to the dual cats. The cats are 2 3/4" diameter of the new Magnaflow spun metallic subtrate design. They flow at least 580 cfm each according to Magnaflow. The exhaust is the Mufflex 3 1/2" back to the new Magnaflow 3 1/2" muffler of the straight through design . I don't see a problem in the exhaust unless for some reason the cats got clogged.

I think I will change out the torque converter first as that is the easiest thing to do and see what happens. Next maybe replace the valve springs with the next stronger spring. Maybe something around 150# on the seat. Once I get this problem solved this motor should really make some good power.

Kevin91Z

iTrader: (1)

BINGO! Dyno Don and I keep telling him its valve float since he has 3/8" pushrods and only 115 lbs on the seat.

What do you mean you're not used to make this level of power thru cats? They dont suck up much, like 1% or less.

1989GTATransAm

iTrader: (3)

Well comparing the datalogging from Saturday's dyno pulls with the ones done last April there is a difference on what I for now will call "converter flashing".

When the pull was done last April in 3rd gear and when the throttle went to 100% the motor would rev up to around 4500 rpm and then the gradual rise of the RPM's would start. Now the motor rev's up to 4900rpm before the gradual rise of the RPM's start. So something is different. Maybe more power.

By the way with the monoblade my KPA/manifold pressure is up a good point on average. So mission accomplished on that part of it. Also no problem whatsoever driving around with a monoblade throttle body. Another old wives tail put to rest.

BadSS

Most all the engines I've built and tuned on were in cat-less cars. Something like Allen's car,, I'd typically fit/run dual 3" pipes. Just an "unknown" part of the equation for me. The suggestion for uncapping was just a quick and easy way to rule-out the cat(s) as a problem,,, and to see what if any power would come from it.