I have a few questions about turbocharging a 300. A little background info. I have just rebuilt this motor. The block was bored .040 and head refaced and completely rebuilt. The cam has lift of .451/.475, adv dur of 270/280 and dur @.050 is 204/214. These numbers don't mean that much to me, being a rookie, except that it is somehwat larger than stock. I think. I have a 4bbl DP Offy intake and was searching Ebay for headers or possibly EFI manifolds when i came across a turbo setup. The seller claims it is a roush racing prototype. It is setup to bolt right on after the stock single out exhaust manifold and bolts directly to stock intake. Setup for a 2bbl carb before the turbo.

Now the questions: Is the turbo going to be able to get enough breath with the stock intake/exhaust? Would a turbo spin up if ran thru only 3 cyl (use EFI manifolds)? Will larger exhaust after the turbo be a benefit? Any problems with stock fuel setup?

I understand the basics of turbocharging, but I do not have any idea what effect it would have on my motor/driveability by just bolting it on. Thats where you guys come in. FYI, this is a 79 2wd F250 in North Dakota, so emissions (what emissions?!?) and all of that are not a factor. I do not promote pollution, but.....

Thanks
Steve

 

I can tell you that if that is on ebay, i wouldnt trust it without thorough research.

also, you don't want to run a turbo off of only 3 cylinders. Those cylinders will have much higher backpressure than the others, and can cause problems. Also, a turbo set up to run off of all six, is going to plain suck on just three.

A larger exhaust will be a benefit. When you have a moded enginge, usually the same mods will yield you more power gains than from stock.

A Turbo 300 is awesome. Maybe mine will get one some day.... yeah right. I need money

 

I'm slowly making progress with mine- twin turbos, EFI, and homemade intake and exhaust manifolds. Sure to be a real head- turner when done. It may be just me, but I really don't like carbs+turbos. Heat and raw gas- count me out!

 

Hey Jared,
I am still deciding weather or not to go to the 240 SBC V head. Maybe you can help me decide. If I go to the expense I want to have a 'noticble' seat of the pants difference. Can you give me any input? Also the same question goes for updating my points dizzy.

Thanks in advance.

 

I would do the SBC valve conversion, but forget the 240 head. My 300-6 n/a with a 240 head is making ~9.2 compression. That's a little too much to run boost against. What I am doing is using a stock 300-6 head, with the SBC valves. This gives much better flow over stock, and with the right piston combination, you can keep your compression in the 8.0:1 range that the turbo needs. Any more, and you are asking for race gas or massive detonation under boost.
As far as points go, I would recomend ditching them in favor of a DUI system from Performance Distributors. Mine cost about $375 delivered COD, and was well worth it. Nearly any electronic system will run circles around a points system, but this one is the best, plus it's only one wire to hook up. E-mail me if you have any further questions.

 

why would you spend money on putting a turbo on a truck motor it makes most of it's torque and HP in the 2k rpm range which is not enough to really spoll up a turbo. that is why they put superchargers on trucks not turbos

 

well if you think about it, most trucks have big *** engines, so even at 2k rpm that's plenty of exhaust flow to spool up a small turbo. Also, since the torque peak is so low, its great to keep that low end power and have the turbo enhance the top end, then you get a real mean power curve.

 

also turbos allow for normal power for normal street driving and when ya stomp it, it makes its power boost...ya know...tubro lag while a supercharger is power as soon as u stomp it...better for fuel economy i guess. but also a turbo set up wont kill power that it takes to turn the charger over a turbo that uses exhuast gas.

 

You can spool a turbo at idle if it's sized for that. A turbo is no different than any other performance engine component; if it's matched to work with the rest of the system it will work very well.

 

This question will make my lack of knowledge blatantly obvious. I hadn't thought anything about the compression ratio having any effect on the turbos performance. Not that I was planning on a turbo when I assembled the motor last summer. I am not sure how to accurately figure compression ratio, since I don't know the volume of the head, or exactly how much the machine shop planed off of it. If I remember correctly, I used dished pistons, which I suppose would help to lower the CR a bit. Thanks for the replies, I'm learing a little.

Steve

 

I hope you used forged pistons.

 

look at my posting [96 turbo] lots of low end power

 

Milling the head won't raise compression much, maybe a tenth of a point or two. I know of one turbo car here that has run up to 15 psi with 10.5:1 compression on pump gas, but it is an LT1 Camaro with EFI, knock sensors, etc. 9:1 should be OK as long as you run premium fuel, but it would be pretty difficult to get over 9:1 out of a 300 by accident. That cam has fairly low duration which will limit how much boost you can safely run.

I agree with the above post about running a carb and turbo together. Putting fuel into something that hot on a regular basis is asking for trouble. I know it's been done, but so has going over Niagra falls in a barrel.

 

Yet every revolution you a mix of air/fuel into a burning hot combustion chamber. In fact the raw head temp is almost guaranteed to be higher than any boost anyone on this forum is likely to run. I'd be willing to bet the exhaust gas that is recirculated is hotter than the intake charge air. A heated carb plate is probably hotter than a couple PSI on a proper turbo setup. Picture summertime with an open element air cleaner in the texas heat or something. You're talking some serious underhood temps, yet noone fears an explosion....


-=Whittey=-

 

that is... unless they're driving a chevy.