Hi there

I'm fairly new to this but i've been lurking for quite a while and really enjoy the site. Good work to everyone involved.

I'm interested in adding a turbo to my slant six (in a '67 belvedere I 2dr sedan). The engine is from a 1970 duster and is of the 2bbl variety.
I have a turbo and carb from a pontiac 301 firebird (1979-81?) and do not know the specs for it. Most of the stuff i have been able to find out is that most turbo 301 guys felt that the turbo was sized too small for the 301. I'm thinking that it would then be sized right for my slant six. The set up is complete including the special rochester 4bbl with the enrichment circuit, especially for the turbo. Will this turbo work for a stock /6?

My other question revolves around timing curves, etc. What sort of curve or ignition parts will be needed (i.e. boost timing retard-msd box, etc.)?

Thanks in advance

Chris

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chris
1967 plymouth belvedere I
/6

Hey Chris,

Welcome to the site. I'm relatively new to slant 6's myself but there are a few things I know about forced induction. First I know that you'll have to get a 4bbl intake to run that carb on. I hope you got the mounting flange for the turbo as well because you will have to modify your exhaust manifold to accept it. A reputable machine shop would be able to do this for you (unless you're a certified welder). You could probably run 6-8lbs of boost on pump gas before worrying too much about boost timing controls. You will have to back the ignition timing off a few degrees. You'll have to fine tune it on a dyno for max performance. You'll also want to get a cam with slightly more lift and duration, otherwise your turbo will be blowing most of the pressure made out of the wastegate and it's all for nothing. Use a bigger cam and allow more air/fuel to enter the chambers. This will easily get you into low 16 second quarter mile times. Spend a few extra bucks on head work and bigger vavles and you'll be hauling down the quarter. I would recommend doing a rebuild on the engine before you turbo it.

-Don

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Forget the flowmasters...here come the good ol' GLASSPACKS!!!

Duster, the Pontiac 301 setup is a draw through. So he won't need a four barrel manifold. Instead, you can make a J-shaped pipe off the exhaust, an adapter for running the discharge side of the turbo to the stock intake manifold, and that's pretty much all the fabrication required. The stock cam should work reasonably well with a turbo; turbo motors generally do not like big cams. (If you're "blowing most of the pressure out the wastegate," something is very wrong - the wastegate is in the exhaust.) I'd get those parts fabbed, add an MSD Boost Timing Master (I'm using one on my turbo project too) and fire it up.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

The draw through set-up will be pretty easy to install but you will have to make some brackets to hold ith unit solid to the engine.

The biggest issue with these is to mount the assembly so you do not get fuel "puddling" in a low spot. Setup the mounting so fuel will run through if you were to pour raw gas into the carb base. You will find that this is not as easy as it sounds. Hood clearance becomes a problem with a turbo assembly sitting on top of the intake manifold in a way in which raw fuel will run through it.

I find that you have the most room if the turbo is mounted back by the firewall.
Here are some links showing draw through set-ups:
http://www.slantsix.org/articles/turbo- ... rticle.htm
http://www.1962to1965mopar.ornocar.com/schmid.html

thanks for all the replies. Matt is correct: it is a draw through set-up, so i figure the trickiest fabbing will be hooking up the exhaust flanges and mating the intakes but shouldn't be too much. I was mainly worried about correct sizing and timing issues. I don't want to change the cam if i don't have to. i just put the motor in and got it running-took it for a spin toady. whoo hoo

chris

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chris
1967 plymouth belvedere I
/6

well, I never claimed to be familar with 301 turbo t/a's either I thought it was a blow-through(never saw one up close and personal). Yeah you can use a stock cam but you won't nearly as much performance. With a higher lift cam you can get the same boost pressure but more air volume which is what really counts. Just a turbo with a stock cam and carb, you won't get a big improvement...you'll be in the 16's...IF you've got it tuned perfectly. You can easily make an n/a sl6 run those kind of times. In my personal opinion...if you're going to turbo a sl6, you might as well swap out the cam and run a 4bbl built to handle boost and go with a blow-through set-up....that way you can run an intercooler too. But that's just MY opinion. Well, at any rate, good luck with your turbo project.

-Don

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Forget the flowmasters...here come the good ol' GLASSPACKS!!!

Well, given that a 16 second car would be 3 seconds off the stock 1/4 mile time, I'd say that's still a respectable improvement. I have not finished my turbo project, but I have done some mock-ups on Desktop Dyno. Turbos work well with fairly mild cams. The Mopar Performance "17 second" cam - basically the stock one with a little more lift - can make around 300 hp in a combo with 10 psi of boost. While the extra lift did make somewhere around 30 hp (maybe it was 50) more than the stock grind, what I meant to say was that turbos do not need wild cams. An RV grind will work well in a turbo street motor.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

FYI, the Drake's Simca has a MP 244 deg cam (essentially stock), and multi-point EFI, and at about 10 psi boost it has 285 RWHP. Good enough to run 13s in an A-body...

Lou

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Home of Slant6-powered fun machines since 1988

From everything that I've read you're better of with a stock cam unless your going to run greater than 14 lbs of boost . In the book "Maximum Boost" the author states that it is hard to find a turbo cam that works better than the stock one, and that if you leave the stock cam alone you will generally be much happier.
Bob D

Corky Bell is quite knowledgable, but he has a tendancy to freely mix his opinion with facts, and not tell you which is which. And sometimes his advice does not apply to all situations even if he implies it does. For example, he claims you do not have to upgrade anything else in the drivetrain if you install a turbo, but running a stock 7 1/4" rear behind a turbo slant seems a little bit risky. In the case of camshafts, cam technology has improved considerably since the last slant six came off the assembly line. The Mopar Performance cam P4120243 is essentially a stock '71-'77 cam with 0.030" more lift. I haven't personally dyno tested them to see which makes more power on a turbo, but Desktop Dyno implies this cam would improve power a bit. But the stock cam is still likely to do better than a cam meant for a wild naturally aspirated buildup.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

I agree that a wild cam shouldn't be used with a turbo. In fact, you probably could run a stock cam with a mildly ported head and possible oversized valves and get the same affect as a cam with slightly more lift on a stock head/valve combo. It's basically about airflow. I really wouldn't want a lopey idle with a turbo...lol, goodbye low end torque. I believe someone said previously that the "17-second" cam works well with a turbo...I agree...maybe I'll try it on my upcoming turbo project. Sure wish I had Desktop Dyno

-Don

_________________
Forget the flowmasters...here come the good ol' GLASSPACKS!!!

You never mentioned your turbo when we chatted the other day . . . what's the status with the draw thru instalation project?

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Cheers!
Al T