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How much boost pressure can stock 83' 350 handle? E85 conversion

893 Views 25 Replies 10 Participants Last post by  johnsongrass1
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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· 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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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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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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Ethanol produces peak pressure much later than gas and the pressure rate ramp is somewhat digressive so it tends to be easier on pistons.
Ethanol doesn't detonate like gas, it's the ring land packing, not detonation, you have to watch for. Similar looking results, different process how is happens.
EGT's are also lower.
 

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The lower the ethanol percentage the richer the carb gets. Cooler weather and adding fuel go together so the change isn't as dramatic as it may seem.

Alcohols can support using more compression but it's not a requirement. It works with 8:1 engines the same as 15:1 engines. AFR's and igniton lead both are similar on the testing I've witnessed.
On the SBC 383 test mule, swapping pistons from 9:1 dish to 12:1 domed, everything else stayed the same. AFR's and timing requirements changed very little. No more than changing intakes, heads, rockers, or anything other typical rodder combination. It made about the same peak torque/HP, but more mid range torque. That's inline with methonal as well. They are torque fuels. What did happen thoough at 12:1, it was less sensitive, I.E. a little wider tuning window. I'm unsure as to exactly why.
 
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