Early shots of my modifed TPI intake.

Going for plenum volume, ~550 ci internal.

TB's are moved to ahead of the blowers, still need to open up the front of the TPI upper and fab up a adapter from 4" round to 4" oval.

 

Nother shot

 

Interesting! How did you come up with needing 550 ci of volume? Have you emailed with Scot Peisch (sp)? He's one of the B-body/Impalla folks up in NH (very good with electronics) and built a large plenum box for his LT1. He opened up the roof of the LT1 plenum, and has a hexagonal shaped cylinder that bolts on top. I don't recall what his outcome (good/bad/worthit or not) was... For the oval to round adapter, I made one for the TPI intake, but it's for 3" round. I took some sheetmetal, cut to the circumference of the oval, and welded the seam to form a ring. To lay out a cone, one end is the 4" round circumference, the other end is the oval. The distance between the two is the steepness. Connect the lines, cut it out, and weld the seam together to get the cone. The 2 prong welding visegrips held the seam tight for welding, while giving access down the seam in the middle.

 

Im just trying to visualize this
the old TPI unit and top half of the runners will be gone? it will be like a viper? two plenums? one TB each?

 

I met Scot last weekend.. Still grinning from the blast in his 6 speed SS.

He didn't have the upper on tho.. Did explain it in detail to me and RBob, and a few others..

After talking with Grumpy, I started drawing this up, then talked with Scot, who also added some interesting info, I came up with this.

The new engine is going to be 306 ci, and "large" plenum theory is it should be 1.0 to 1.5 times the engine size.. I'm sitting at 1.8 to 1. Going to shorten the boxes a bit.

BW

 

Yes two TB's, but each one will be ahead of the blowers. I am going to run a single 4" pipe out of the intercoolers into where the stock TB used to reside.

It is one plenum, ( i need to cut thru still) and yes to runners are cut and the lower is siamesed 3 inches.

BW

 

Very interesting in deed!! I can't wait to see the finished product, as I too am considering modifying my TPI intake in a somewhat similar way. Keep us posted, adn keep up the great work!

 

Scott just happens to make it out to OH from time to time.
Yes, he got the idea on one of those rides, and it did make a positive difference.

We'll have to wait to spring to see the new engine and still classified mods..

 

Saturn5,

how are you going to cap the ends of the extra plenums? If you are welding that all togther, you might get more benefit by getting rid of the old plenum altogether, and fabbing a complete box.......if you are already welding, it might make assembly easier than trying to connect those bolts on the side of the plenum....not criticizing at all, looks very unique, just thinking it might be benificial, maybe gain more plenum volume that way? Also opens up options for inlets on the font of the plenum....anyway, just some ideas......keep up the excellent fabbing...interested to see the results....
Joe

 

Saturn5,

Why do you want that much plenum volume for a boosted application????

 

Well, you guys have the know how, and the real life experience to back this up, I hope your theory's are correct and everything flows smooth for you.

My question is ! In a Naturally aspirated application, is there any benifiet to more plenum volume, such as a 350 TBI Would it be a via project, to take on? perhap creating a bigger plenum beneath a TBI unti, providing that you maintain air flow and fuel atomization?

You just got me wheels spinning is all.

 

A buddy is going to TIG the ends shut and weld the tubes. The side of the TPI upper is fully open, (I'll post pics soon). I thought about building a super ram clone, but decided this would be easier to fabricate and the volume suits my needs.


I can't explain the theory real well, other than it works. I have talked to several people who have done this idea and have had positive results, both NA and boosted.

Also.. look at this buick V6 turbo INDY plenum..



This thing is huge.. for a 231 cubic engine.

Might want to look for a old crossfire intake and build a new top plate.

BW

 

hey I've seen that buick intake before, now where was it at? hmmmmmmm seen a 6 spd impala before too...

strangest things no :-) lol


Im curious as well to the relationship of plenum volume to engine size on a NA motor, hogging out a factpry intake for the GTA and redoing the runners as well might be able to hack some other stuff up too....


Far as the Formula goes i just want to get it under way with my eaton m90 and then worry about the plenum volume :-)

Ward reinspired me with his 'Bu for TPI and Eaton SC

later
JEremy

 

Huh, just thinking out loud:
- Increased plenum volume… but how are you planning on connecting the runners? Sounds like you’re thinking of welding them to the bottom of the plenum. If that’s the case I suspect that it will be a real pain with gaskets
- Moving the tb’s in front of the superchargers should quiet things down but could cause a real problem if your plumbing pops off. I wouldn’t dare do it unless everything between the blower and the intake valve is made out of metal without any easy to separate joints… (which sorta leads to the thought, connect the blowers right to the sides of the plenum.
- Typically, plenum volumes of around .8 to 1.5x the engine displacement work well NA, as boost goes up so does the plenum volume that works well. Plenum volume is pretty much defined as the volume between the TB and intake valve… In your case you’re going to end up with quite a bit of volume in plumbing and blowers. I suspect with the volume that you’re going to end up with your throttle response will entirely depend on the blower RPM. That would make a great track combination, but I’m not sure that that’s a happy situation on the street.
- I’m confused on the runners and then siamesed base… the runners will just end up a restriction… If your going to go this far why not dump the stock runners completely and have the whole setup siamesed?

The big thing I wonder about (been playing with similar ideas involving a crossfire or crossram base) is what happens with the cylinders that fire next to each other in the firing order and are physically located next to each other. In a carb intake where you’ve got a homogeneous A/F mixture this isn’t that big a problem, you just increase plenum volume a little and extend the port wall between them a little more. FI I it should be an issue. My instinct (especially running batch fire) is that the first cylinder will run rich, and the second will run lean. I know that this actually does happen on the LT1 intake, and I’d imagine making the runners even shorter and going to batch fire (LT1’s have sequential) will make this worse.

 

Oh, anyone know where to find pictures/info of this impala setup?

 

Idea is to weld the box tube to the runners. then the original upper plenum and modified runners bolt in like stock.

I'm still reall undecided to running twin TB's, and I may just stick with a "normal" location TB. Popping tubes off would be a bad thing.. . I thought going straight into the boxes with the outlets, but then I would lose the intercoolers. So far they seem to work fairly well.

Yeah, and another good point for keeping the TB in the stock location. Also trimming the boxes to 14" length each to get the best volume.

I'm going to do the runners too, just haven't cut them yet.

I thought about adapting a xfire intake, but that would also mean adapting injector bosses and rails. I'll fiddle with the TPI stuff for now, and if it doesn't pan out.. I'll build something else.. :duh:

On the second, will have to wait and see..

BW

 

Give Grumpy a holler about Scott's Impy SS T56.

It's a hoot.

BW

 

If you are worried about cyl 5 and 7 firing next to each other,
get your cam ground switching 4 and 7 (18736472) instead of
(18436572). This is worth a few horspower and makes your engine run smother.

 

That’s a hell of a lot less work then that you’re doing will add up to… Hell, if I had a extra base sitting around I’d even consider doing one just to tinker with it. Even with the original throttle body setup on it I like that setup better then the TPI, and making a hybrid would be sweet. Just trace the top to a sheet of aluminum, drill for injectors in the right places and then make an adaptor to mount the TPI TB to the top of it in it’s original orientation. You can make the internal volume of the adaptor any size you need to get the plenum volume the size that you want, and I’d probably just weld it out of steel to avoid finding someone to weld aluminum.

If all you wanted to do is run a crossfire intake as a port setup it would only take a few hours to do and most of the parts you could get at the hardware store. I’d run rails from the LT1 sitting in the corner of my garage or even stock TPI rails, you’d have to futz with the fpr setup some to make it work (OTOH, I’ve modified a bunch of mustang FPR’s to be mounted remotely, don’t see why I couldn’t do that here). I could see myself getting hung up for a while messing with cutting out the EGR passage and opening up the runners (I don’t remember exactly how small they are, but they’re small as cast).

BTW, if you get a later one (’84) the runners are already partially siameesed (they were made with holes connecting the adjoining runners), and for a boosted application it would be far superior to the original TPI layout (a wet flow manifold actually carrying fuel which will cool the intake charge, but the separate injectors for each runner should eliminate most of the bitching that most people did about the various crossram designs (which I still contend were tuning problems and the need for slight tweaking, not design problems)

The real question is how to make it look cool…

 

Stop... your making the voices return..



BW

 

hey, just curious now..

if the TB was before the SCs, wouldnt EVERYTHING behind them become plenum volume? incuding the intercoolers, the tubing, ect?

 

Huh, do yours actually go away?


Really?


Mine just sorta wander in and out from a constant drone to some screaming, then there happen to be a few people that manage to 'insert' some arm flailing in there....

When it gets bad it's time to reach for the JD to numb/calm things down.

You are about 4 or so posts behind... I already said that in my first post to this thread...

 

You see now there all fired up and chatty....

Theres a couple xfires on ebay for cheap..

Dave W has a small write up on a carbed xfire conversion...

Could also add additional injectors.. makes Bruce's vaporization possible..


Ahhhhh!!! < best joan collins > scream.


Your a bad person....

 

Heres one for the voices....

Crossfire lower...

New top plate.. add one M112 Eaton.


Hmmm...


BW

 

WIERD! ive had that same voice talk to me....

then a 2nd one chimed in and said to cut the plenum off of a LT1 intake and use that instead with a M112.............

 

that porting to make the ports full sized is alot of work, would a singleplane carb manifold work as well?

 

heh, that’s one variation of the evil voices in my head for my truck… building up the crossfire 305 out of my ’83 to replace the 350 in my ’92 truck.

305: better detonation resistance, better gas mileage…
crossfire: probably the best low end that I’ve ever seen, the 305 crossfire is MUCH better till about 3500rpm then my L98. that car is probably the most fun of anything I've ever owned in the stop light granprix or just doing flat out stupid fun stuff... torque is good
Blower/Turbo: sized for what the truck uses… right now it’s all done by 4000-4500rpm, and I really don’t need more. It spends 99% of its time sub 2000rpm. I was thinking either a small turbo that could fully spool by 1500rpm under load or an M90 bolted on to the top of the crossfire with somewhere in the 4-4.5:1 pulley ratio (that would spin it up to 18000 just like on the LTD). Both would happily make 350-500hp by 4000 or so rpm with almost a tabletop flat power curve and 700+ lb-ft at about 1500rpm…

OHHHH YEAHHHHHH…

For performance use, unless you feel like getting really intimate with a grinder I’d suggest you start with one of the cross ram copies, just because they’ve got exactly the same layout, runners tuned for the same frequency but the runners have almost 2x the crossection.

The reason that the LT1 manifold doesn’t even touch this setup is that with the crossfire/crossram you’ll be able to use the fuel for it’s intercooling effect, and packaging and modification will be much, MUCH easier.

I don’t think an M112 will fit if you want to retain the distributor, but I’m sure it could be made to work.

 

Going to scrounge up a xfire to give the voices something to gossip about...

Been thinking on how to adapt one to work with the stock TPI TB..

Take a look at this.. upper intake off a 460 EFI. hmmm.

this is begining to get interesting....

 

heh, I just fed my voices also... just got a dirt cheap deal on an HX40 turbo... should be good for something in the 7-800hp range

 

Hehe.....


feeding the need of the darkside ehh?


hey.... you got approx dimensions of a xfire lid??

might stop by the scrap recycler for some plate.

BW

 

It's a diamond approximately the size of the whole space between the valve covers (literally, there is only about 1/2" of space, just enough to get a socket down to take a set of old school, parameter bolt valve covers off).

If you need more precise #'s I'd have to drop my brother's house and measure the '83... if I can get the hood open (I know you saw the pictures of the tree on it)

Oh, and the dark side took over long ago... why did you think I wanted to measure those pistons? BTW, it looks like I can cut over a 40cc dish in them if I really want... can you say BOOOSSTTTT!

(though i'll probably see how fast I can make a stock L98 go first...)

 

here, you can kinda see it in this picture, basically nothing but the lid and valve covers with just enough space for the water neck and distributor

 

Nope.. that gives me plently of reference. thanks, BW