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Hello, does anyone know how much boost pressure i could safely give a chevrolet 350 with a 9.0:1 compression ratio without modifying the internals and how many hp would that be about?

My plan would be to convert it from gasoline to E85 (85% ethanol/15% petrol) to avoid detonation and possibly get around some of the european emissions standards before putting turbos on it.

The turbo would be something like a single or double t3 Mitsubishi TD05 16g turbo used on the volvo 2/7/900 series rated for 0.9 bar or 13 psi each

But the question is how much boost do YOU know a stock 350 can handle, i would be happy with "only" getting 400hp from a 200hp stock engine, but am i dreaming or is it possible?

Sorry for bad grammar, hope it is not too offensive :p
 

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If you want to run any boost you need to pull the pistons and gap the rings. Then your talking about small valves in the heads and stock rods.

You will be better off changing the heads along with the pistons to make a higher NA engine that has only one tune to deal with.

A reliable 400hp on early sbc is actually a expensive number to reach. Your talking about adding 100 to 150 hp to the engine and a sbc will fight you. The magazines and such may show 400hp builds. But thats often risking things in a dyno at 5500+rpm. It is not a reliable street driven 400hp at sbc.

Now. If you dont care about longevity then I would add 100hp using nitrious and a progressive timer running the thing rich with something adjusting the timing. Eventually the rings will seat or you will have a missfire and the piston will end up in the oil pan. But you may get a few runs out of it before that happens.

A nitrious plate setup can be removed in an afternoon to return things to stock appearance easily enough.
 

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My son had a 96 lt1 camaro. Put a pro charger on it . Ran it with a 9 lb pulley on it. Then he said I'm going to put a 12 lb pulley on it. I said I wouldn't. 2 days flattened all the top ring lands on the pistons. On the street. Stupid ,But guess who pulled it all apart to fix it. Yea you guessed it. Who's dumb then. That's what fathers are for right. NOT!!!! Live and learn but I don't I just live.
 

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Superchargers are the most American, and quickest way to find issues that will arise in your engine. Which often leads to catastrophic failure. And not every time it is the engine for example, cold blood murder of tranny and transfer case.
Black Motor vehicle Automotive tire Road surface Pollution
 

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Race it, Don't rice it!
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would you suggest 15 PSI on e85 with no intercooler? I keep hearing about widely fluctuating alcohol content at pumps.
E85 latency means inter-coolers aren't as effective as gas. I don't mean NOT effective at all, just much LESS effective and often not worth the weight and plumbing hassles.
Example, Our circle track engines will condensate the intake and carb in damp weather similar to M1.

Your not at all wrong about the fluctuation of ethanol content/percentages but there is much more to that.
First, on the dyno there has been very little to next to nothing in power between 70-90 percent on the typical engine. Even when that 70-90 is enough to change the carb setting from rich to lean it still hasn't made a lot of difference. Even on 87, the E percent fluctuates from 3-10 according to the EPA. E85 can be 53-83 by EPA law. Now, if your bracket racing on .001 dials and consistency is the of the upmost importance, it could have a factor for you. but reality, if your on that level, you should be able to work around it easily like buying barrels, or mixing, or in my case, I fill empty barrels, at a local pump I know and have tested at 75-80 and tune to that. Also, there is a VP dealer locally selling pump E, Not VP C85, but Pump E for $3.10/gallon. The owner personally sets the pumps at E90 so you can make what you want. I run it as is. Add 10g's of 87 if you want E85. Simple as that.
I bought 150 gallons last spring and it's been perfect. I still l have about 60 gallons left. What I don't use sits behind the shop on as pallet till Feb. No problems.
So yes, it's true, there are some fluctuations in percentages from region to region and pump to pump, especially the blender type pumps. That might matter for a all out max effort guy, for a street guy, it's not likely a factor and even if you think it is....It's easy to work around.

PS: That is unless Pump E is taking away your sales...understand me? :cool:
 

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My son had a 96 lt1 camaro. Put a pro charger on it . Ran it with a 9 lb pulley on it. Then he said I'm going to put a 12 lb pulley on it. I said I wouldn't. 2 days flattened all the top ring lands on the pistons. On the street. Stupid ,But guess who pulled it all apart to fix it. Yea you guessed it. Who's dumb then. That's what fathers are for right. NOT!!!! Live and learn but I don't I just live.
My guess would be it wasn't the pistons inability to withstand 12 psi, but the fuel systems' inability to provide enough fuel for that 12 psi boost level.
 

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Id blame to tune up. Cold plugs blow out the rings lands.
First of all I'm mot asking your opinion. And since you don't know my tune up That's all it is is an opinion. I'm stating what happened trying to tell the o.p to be careful. The pcm was tuned by someone who runs these combinations. He set the fuel maps selected the plugs and the timing map. He said the stock pistons are iffy at best. But you seem to have all the answers.
 

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Race it, Don't rice it!
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First of all I'm mot asking your opinion. And since you don't know my tune up That's all it is is an opinion. I'm stating what happened trying to tell the o.p to be careful. The pcm was tuned by someone who runs these combinations. He set the fuel maps selected the plugs and the timing map. He said the stock pistons are iffy at best. But you seem to have all the answers.
So you gave an opinion on something that no one asked for, yet here we are.
It appears if everything was just right on your junk. Professional and all.... and yet it still broke......okay.
Go ahead, get snarky with the guy trying to help you not blow up stuff.
 

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Something everyone is missing

The OP wants to put boost into STOCK 1983 heads and cam potentially not even touching the rings.

I am assuming some kind of blow through carb will be used. But I am also thinking the runners will be unequal.

Small valves + unequal runners+ additional air= some cylinders running lean.

How much boost can the OP run with some cylinders running lean on a untouched stock long block?

I wont go into it much. Just saying the same stuff that can be done with a factory LS often cant be done to a factory SBC regarding the "safe" amount you can run by simply changing the rings and injectiors/carb.


Safe amount on a stock sbc longblock. Maybe 4psi which considering all the cost and modification required is pointless when you can make more power with similar cost by running diffrent heads and a bit more compression NA.

The real difference comes with the tune. NA your tune is set. With boost and no supporting electronics your talking boost levels and air fuel levels that will vary from sun up to sun down as well as through elevation changes.
 

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So you gave an opinion on something that no one asked for, yet here we are.
It appears if everything was just right on your junk. Professional and all.... and yet it still broke......okay.
Go ahead, get snarky with the guy trying to help you not blow up stuff.
The question was from the o.p. about how much boost i gave my opinion. He asked the question. You gave an opinion to me I didn't ask for. My post was not in the form of a question. So get your story straight. You 're the one with the cocky know it all attitude. If I ask for help do me a favor and ignore it. Go back and read my post or read it right for the first time.
 

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Race it, Don't rice it!
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You read it wrong or I wrote it too crypticly. I was saying E85 will support more than 9lbs...There are plenty of examples out there to support the theory in carbed and FI varieties. Using youre posted situation as an example, the tune up was off, (doesn't sound like it was your fault) and therefore the engine broke at 9lbs BUT if the tune up is correct, A/F, plugs, wires, ignition and timing, etc, it'll support 15ish, depending on the specifics NOT known of the application of course, it's a general answer to a generic question NOT directed at you.
Using your situation as an example, I suspect the rings loaded up and lifted but it's not because of the detonation/heat as many will think. Professional tuners included. That's gas thinking...Not ethanol thinking. I can provide contact info tfor two guys that have been studying that phenonem for over 20 years and they can explain it way better than me.

I won't bother you in the future. Also, you're more than welcome to use the "block this user function", It's even free! So you don't accidentally get irritated at my opinions.
 

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You read it wrong or I wrote it too crypticly. I was saying E85 will support more than 9lbs...There are plenty of examples out there to support the theory in carbed and FI varieties. Using youre posted situation as an example, the tune up was off, (doesn't sound like it was your fault) and therefore the engine broke at 9lbs BUT if the tune up is correct, A/F, plugs, wires, ignition and timing, etc, it'll support 15ish, depending on the specifics NOT known of the application of course, it's a general answer to a generic question NOT directed at you.
Using your situation as an example, I suspect the rings loaded up and lifted but it's not because of the detonation/heat as many will think. Professional tuners included. That's gas thinking...Not ethanol thinking. I can provide contact info tfor two guys that have been studying that phenonem for over 20 years and they can explain it way better than me.

I won't bother you in the future. Also, you're more than welcome to use the "block this user function", It's even free! So you don't accidentally get irritated at my opinions.
I appreciate the explanation. I won't block you. I guess I took it the wrong way I apologize.
 
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