Blow Thru Carb

[Skylark-69]

Hi folks. I'm currently gathering parts to build up a twin turbo 231 carb'd blow thru set-up.
It's going into a 1969 Skylark. Thought I'd do something different than the somewhat usual GN engine in a classic.

I'm planning on twin turbos to keep the boost/detonation down but still produce good power. It will be intercooled and maybe alky injected. I'm in AZ so alky may be mandatory. My end goal is to run very low 12's on pump gas and maybe high 11's someday.

Here is what parts I have or will have

Edelbrock intake
8445 heads-ported
Block-TBD
Cam-TBD
Crank- Forged or 4.1
2 dot con rods
Stock or Sealed Power pistons
Still working on what carb to get

Turbos:TBD
2 T3's
2 T3/4's
2 GT25's

Any helpful suggestions are welcome

 

[charlief1]

Here's some reading for you.

http://www.turbobuick.com/forums/before-black-non-sfi-tech/294806-repeat-procedure.html

 

[Skylark-69]

Here's some reading for you.

http://www.turbobuick.com/forums/before-black-non-sfi-tech/294806-repeat-procedure.html

Thanks. Good thread. Missed a few things from that one and others. Decided a stock 86-87 cam would be good.
Still need to pick a carb and what size. Being a twin turbo set-up I think that a Q-Jet 750cfm might be a little big.

I posted on the other site and was advised to come here. Something about A.J. having a new person to chat with. :wink:

I have to confess this isn't my first go around with the 231. My first car was a 1980 Buick LeSabre with a 231 two bbl. What a stone. 0-60 in 18 seconds. :frown:

Still, it was a fun car and that little engine just made me think, what if?
I guess I'm just trying to do it the way I wanted to then, but didn't know how to or have the means. Besides, good power from a little 6 is so sick I smile at the thought.

 

[charlief1]

Aj. (dr_frakenstien), Warwagon (Adam), and myself are all trying to get into the 11's, but we're trying to do it in different ways. If you click on Adams name and look at some of the threads he's started you should be able to get a better idea. Aj works for the DOD and is in the desert doing testing right now so he can't post right now. If you click on the second link in my sig it will give you an interesting mod for the draw through set up as far as the turbo, but I'm not finished with it yet due to financial issues. Aj and Adam are using the passenger side header off of the 86-87 cars and it seems to work well for them. If you look under my name you'll also find a thread about moding the 4.1 intake to get better power out of it.

 

[dr_frankenstein]

Yar! Whooo That! Be knowing My Names......


LOL

Whats up? Welcome to B4B.... I like your idea, sounds wicked... i reckon 2 stock 86/87 turbos or two ebay specials would spool fairly well in your engine if you run it on the higher side of compression. I have heard of people blow thru-ing a quadrajet before but I hear the metering is allover the place because it was definitly not designed to do that! LOL (same issue on the holley spreadbore) So I would reccomend a Demon. I have used both draw-thru and blow-thru carbs that they offer and they never let me down.

Electric fuel pump is manditory, as the stock 3.8 mech pumps cant take the boost refrencing to anything higher than bout 10lbs. I have seen the older oddfire nose buick 455 HV pump referenced to 30 or so lbs, but is only good in a stage 2 or an oddfire snout cam. The fuel pressure will have to rise in porportion to the boost since your "blowing threw" the carb. Not really to big of a deal. and is decently cheep from summit.

If your run the biggest possible intercooler you can in the front of that beast i think low 11s could be had with minimal alky support. being that your going twin turbo run the biggest pipes and stuff you can.... volume will be your advantage.

open your heads up to atleast a 1200 fel pro intake and a 1400 exhaust. have the heads milled down to .015 to help up the compression a bit. If all possible, have your machinest offset grind your rod journals .015 positive. this will zero deck the pistons without chopping the deck. (measure twice first) The key is going to be your heads, try to get them to flow as much as possible! run a cam that will wind you up to 6500 atleast. and either a weiand or your edelbrock heavily ported.

A 3200 stall converter sounds about right, i suggest you keep the lock up for a decent highway ride and a set of 3:42 rear gears if your more the highway guy or 3:73s if you prefer a spicy take off.

Whew! i like pabst. can you tell?

LOL

Anyways, welcome to the site.. Charlie, Adam, Jessie, Rich, Freddy are real smart guys and can definitly help ya out.

And Charlie, i got some more funds headed yer way on 10-9

:biggrin:A.j.

 

[charlief1]

Cool Aj. Glad to see you visiting again. Hope everything is good for you and get back here soon. Now if Adam will join in I think it should answer some more of your questions.

On a side note, you gonna make Noble this year Aj? I'm planning on going to meet some of the guys so if you can we might cut down on the shipping for you.

 

[Skylark-69]

Yar! Whooo That! Be knowing My Names......


LOL

Whats up? Welcome to B4B.... I like your idea, sounds wicked... i reckon 2 stock 86/87 turbos or two ebay specials would spool fairly well in your engine if you run it on the higher side of compression. I have heard of people blow thru-ing a quadrajet before but I hear the metering is allover the place because it was definitly not designed to do that! LOL (same issue on the holley spreadbore) So I would reccomend a Demon. I have used both draw-thru and blow-thru carbs that they offer and they never let me down.

Electric fuel pump is manditory, as the stock 3.8 mech pumps cant take the boost refrencing to anything higher than bout 10lbs. I have seen the older oddfire nose buick 455 HV pump referenced to 30 or so lbs, but is only good in a stage 2 or an oddfire snout cam. The fuel pressure will have to rise in porportion to the boost since your "blowing threw" the carb. Not really to big of a deal. and is decently cheep from summit.

If your run the biggest possible intercooler you can in the front of that beast i think low 11s could be had with minimal alky support. being that your going twin turbo run the biggest pipes and stuff you can.... volume will be your advantage.

open your heads up to atleast a 1200 fel pro intake and a 1400 exhaust. have the heads milled down to .015 to help up the compression a bit. If all possible, have your machinest offset grind your rod journals .015 positive. this will zero deck the pistons without chopping the deck. (measure twice first) The key is going to be your heads, try to get them to flow as much as possible! run a cam that will wind you up to 6500 atleast. and either a weiand or your edelbrock heavily ported.

A 3200 stall converter sounds about right, i suggest you keep the lock up for a decent highway ride and a set of 3:42 rear gears if your more the highway guy or 3:73s if you prefer a spicy take off.

Whew! i like pabst. can you tell?

LOL

Anyways, welcome to the site.. Charlie, Adam, Jessie, Rich, Freddy are real smart guys and can definitly help ya out.

And Charlie, i got some more funds headed yer way on 10-9

:biggrin:A.j.

Wow. My head is spinning after reading your post.
I forgot how lousy the Q-jets were for blow thru unless you put them in an enclosure or made special modifications-not going to happen. I was thinking Demon and you just reinforced that line of thought.
From what I've seen on this BB the Weiand may be soggy on the bottom end and I do love torque. The Edelbrock seems to be the better choice for me. I am wondering if there are modifications in addition to porting that should be done to it.
I also don't mind alky, especially if it provides an additional margin of safety. I want this engine to live for a while. Silly, I know.
I had decided on 3.42 gears as well. Really, stop reading my mind.
Can the 86-87 cam be run to 6500 or is a different cam a better choice?
As for exhaust, I was surprised to see people using 2.5 inch for the GN. I dabbled in the import world and they were using 3 inch exhaust for just a 4 cylinder. I'm thinking dual 3 inch exhaust (or larger) in this case.
PBR? Too rich for my blood. Old English 800 HG or Sclitz HG Lager. :biggrin:

Lastly, thank you very much for the info. It's invaluable.

 

[usetaboost]

I'm an Old Spill man myself. J/K:biggrin: I'd rather drink a bottle of scope

 

[charlief1]

While the Ebrock intake does a good job you could also use the factory 4.1 intake with an adapter. Just about the same after porting it out. If you want to see how much it can be ported look for my thread about modifying them. It's a bit labor intensive but it's cheap enough to get one and go from there.

 

[Skylark-69]

While the Ebrock intake does a good job you could also use the factory 4.1 intake with an adapter. Just about the same after porting it out. If you want to see how much it can be ported look for my thread about modifying them. It's a bit labor intensive but it's cheap enough to get one and go from there.

Thanks foir the reminder. Been meaning to look that up. I like to DIY stuff if I can.

Hey A.J., what compression ratio did you have in mind? 8.5:1? 9:1?

 

[charlief1]

Here you go. I have it save in a special folder just for this purpose. Saves a lot of time in the end.

http://www.turbobuick.com/forums/be.../281474-modification-4-1-4-barrel-intake.html

 

[83turbomon]

Wow thanks everybody. ive been taking peoples advice and reading up on the forums, esoecially about the blow through carb.

 

[charlief1]

Keep reading. There's lots to read and it will take you time to absorb some of it. If you have any questions ask and sooner or later one of us will answer you.

 

[usetaboost]

I looked up the price of those demon blow thru carbs with bonnet. over 600 bucks damn! Good thing the rest of the crap can be bought off the board cheap

 

[dr_frankenstein]

Thanks foir the reminder. Been meaning to look that up. I like to DIY stuff if I can.

Hey A.J., what compression ratio did you have in mind? 8.5:1? 9:1?

I would shoot for 9 flat, you need all the torque you can get for such a heavy car, and it will help keep the boost to a resonable level. even if you crank it down on a HOT day your power wont be as dead.

Charlie's 4.1 intake would be an awesome piece to use if your trying to stay budget minded, as Im sure it flows just hot damn.





Charlie, I am going to try for Noble, but I doubt I will make it... im even beginning to question being able to make pinks. The more I tear the truck apart to get it race ready - the more I find things that have been a real issue. So we shall see.......... LOL

A.j.

 

[b4black]

I'd start with a single turbo. Then you can take advantage of all the stuff (exhaust manifolds, etc.) out there for a 86/87 TR.

 

[charlief1]

Cool Aj. Hope you can make it. We could save some shipping that way. I doubt Rich will be able to come but we can always hope.

Good point about the single Rich. I remember one guy that made a bonnet out of a tea pot a while ago and was only running 4-5 psi but it seemed to work well. Lost the link when the last puter died though. Adam is running an 86-87 header set up and turbo. Works well for him to.

 

[WarWagon]

I'm watching the thread! I'm a bit late my puter @ home is dead for the moment, so thanks for work to let me use theirs, lol

 

[Skylark-69]

I thought about single turbo, but felt this would be the easier, better way to achieve my goals.

Thanks for the link Charlie.

 

[charlief1]

I'm watching the thread! I'm a bit late my puter @ home is dead for the moment, so thanks for work to let me use theirs, lol

I know your pain Adam.:biggrin:

Getting the turbos to balance will be the biggest problem. Using two of them can be somewhat problematic to say the least. Do a search in the general section as well as the turbo section.