e85 ?? - Pontiac GTO Forum
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post #1 of 25 (permalink) Old 02-14-2018, 12:50 PM Thread Starter
 
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e85 ??

I am rebuilding my carbs (tri power) and apparently the new rubber is e85 safe. Local stations are now selling e85 (which is very popular with high boosted motors). My question is, would e85 work well in a 400 motor with high compression heads ? Are there other issues I would need to change / address ? With fuel injected cars, you usually need to increase flow ~20%, so I am guessing the jets would need to be changed to a larger size.

Anyone been there / done that and have advice, I would appreciate it. Thanks

Chris

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #2 of 25 (permalink) Old 02-14-2018, 04:57 PM
 
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I've been wondering the same thing, cij911. I've got a '68 428 HO with the 670 heads and the original spreadbore Qjet manifold, and 4 bbl E85 carbs are available, but I'd rather run a tri-power setup, if possible. I've never read anything online about anyone doing it...
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post #3 of 25 (permalink) Old 02-14-2018, 05:17 PM
 
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Garage
FWIW Recent Engine Masters covers this...

GTO Jr. - A.K.A. SPRINT 6
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post #4 of 25 (permalink) Old 02-14-2018, 06:00 PM
 
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It can probably be done, but will be easier & probably even cheaper to use Torco Accelerator octane booster.

There are lots of E85 Holley carbs & kits.

http://e85carbs.com/

There are big Roch-to-Holley adapters. I suppose this would allow you to use E85 Holley 2-barrels. ???

https://www.ebay.com/itm/Fits-Pontia...-/263452933662

There are a few guys who build E-85 Q-jets. So, I assume there are guys who can build E-85 Roch 2-barrels. But, it usually involves more than just a jet size increase.

e85carbs.com will convert your Roch 2-barrel. This quote is taken from their website, near the bottom of the page.

" Convert your Rochester 2brl to E85 We can convert your 2 barrel carb quickly. This includes normal replacement parts for E85. If your carb needs an overhaul we can get that done for an extra charge. We can convert most 2 barrel performance carbs.

Purchase your conversion here with PayPal or credit card, print out your recipt and Ship a copy with your carb and send it to us at: Rob Mix Services, Inc.*465 North Street * Saint Paul, MN 55130. This overhaul can take 1 week in shop but we try to turn it sooner if possable. Return shipping will be added at checkout about $24.50 "

http://e85carbs.com/

Several carb shops build 2-barrel Rochs for circle track racing. They use high flow needle & seats, small floats, and are drilled for Holley jets, in order to flow more fuel. So, I figure one of these guys could build a good E85 Roch. I'd talk to SMI about it.

https://www.smicarburetor.com/produc...9/productID/60

Also, the actual ethanol content of E85 can vary greatly, from area to area, and can change from season to season. If you switch to E85, you need an ethanol tester, in order to verify the ethanol content, before using it.

Last edited by bigD; 02-14-2018 at 07:47 PM.
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post #5 of 25 (permalink) Old 02-14-2018, 08:13 PM Thread Starter
 
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Well Torco Accelerator will get very costly if one drives there car a fair bit.

e85 is an easy upgrade on newer fuel injected cars, but appears to be a bit more of a challenge with the older cars. Given the cheap price of e85 and the effective octane rating of 100 +, it would be great for the original high compression Pontiac motors. That said, I will probably just stick to a low compression tri power ....

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #6 of 25 (permalink) Old 03-01-2018, 01:56 AM
 
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That's what I thought, it's no rap on anyone who replied, but I still have seen no one who has actually run E 85 through a '66 tri power. I've seen comparisons between the racing gas and E 85, but I'm not buying 55 gallon drums (at what, $400 or more?) of racing gas to store in my garage! And I do want to drive the car at least 5K miles per year. Changing to open chamber heads, and re-rebuilding the motor with dished pistons to drop down to a 9:1 compression ratio would lead to a huge loss in torque and h.p., right? Even though everyone says watch out for the winter E 70 versus summer E 85, why is that so bad, and how do you fix it? Add gallons of pure ethanol to the tank right away if you're not at 85% at the pump? What happens if you temporarily go from E 85 at 105 octane, to E 70 at about 100 octane in a 10.75 to 1 motor? Retard the timing a couple degrees til you get the ethanol back up? I live in the corn belt so E85 is cheap and readily available at all the local Kwik Trips. bigD, thanks for the links and the advice, but we know that a tri power is more than a two barrel carb in that when the end carbs dump open the mixture is probably not the same as a Holley 4 bbl or a Q jet and I'm wondering if you can get all six barrels to work right with E 85, and I've never heard that tale. If anyone has, please let me know.
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post #7 of 25 (permalink) Old 03-01-2018, 08:35 AM
 
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"...E 70 versus summer E 85, why is that so bad, and how do you fix it?..."


If the carb was built & tuned correctly for E85, and you feed it E70, the mixture would be too rich. Would probably need smaller jets, at least. Don't know exactly how much difference a 15% drop in ethanol content would make. Hey, a guy posted that he knew of a Dodge pickup with a 2 barrel that switched from pump gas to E-85 without changing anything & it ran just fine. But, even if that was true, somehow I don't think I'd try that on a Pontiac.

http://www.superchevy.com/how-to/add...5-fuel-switch/

Last edited by bigD; 03-01-2018 at 09:00 AM.
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post #8 of 25 (permalink) Old 03-01-2018, 09:49 AM Thread Starter
 
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I have run e85 with modern fuel injected cars (high boosted performance cars) and it really was relatively easy to get the benefits of a pseudo race gas (e85). Essentially with I swapped the injectors for larger flowing ones and remapped the fuel and timing curves (ECU tune). I would think for our situation (Pontiac GTO) all we would need is to make sure the gaskets and fuel lines were ethanol compatible and run larger jets.

I am seriously looking into it and will document what I do for others.

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #9 of 25 (permalink) Old 03-01-2018, 12:14 PM
 
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Quote:
Originally Posted by WheelHorseman View Post
That's what I thought, it's no rap on anyone who replied, but I still have seen no one who has actually run E 85 through a '66 tri power. I've seen comparisons between the racing gas and E 85, but I'm not buying 55 gallon drums (at what, $400 or more?) of racing gas to store in my garage! And I do want to drive the car at least 5K miles per year. Changing to open chamber heads, and re-rebuilding the motor with dished pistons to drop down to a 9:1 compression ratio would lead to a huge loss in torque and h.p., right? Even though everyone says watch out for the winter E 70 versus summer E 85, why is that so bad, and how do you fix it? Add gallons of pure ethanol to the tank right away if you're not at 85% at the pump? What happens if you temporarily go from E 85 at 105 octane, to E 70 at about 100 octane in a 10.75 to 1 motor? Retard the timing a couple degrees til you get the ethanol back up? I live in the corn belt so E85 is cheap and readily available at all the local Kwik Trips. bigD, thanks for the links and the advice, but we know that a tri power is more than a two barrel carb in that when the end carbs dump open the mixture is probably not the same as a Holley 4 bbl or a Q jet and I'm wondering if you can get all six barrels to work right with E 85, and I've never heard that tale. If anyone has, please let me know.
Actually it is not as "huge" a loss as many think. Check out the Wallace Racing Calculator:

Wallace Racing - Calculate New HP From Change In Compression Ratios Calculator

Hope this helps.

("Your old Compression Ratio of 10.5:1 and HP of 350 is now calculated
as a Compression Ratio of 9.5:1 and 346.29 Horsepower.")
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post #10 of 25 (permalink) Old 03-15-2018, 03:28 AM
 
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Hmmm- I think that Calculator might need some new batteries in it. You can find online an article I read from Hemmings magazine, Aug 2005, called "Tin Indians." They interviewed "Jim Taylor, the legendary Pontiac engine builder from Phillipsburg, NJ." He said; "One point lost in compression equals 50 lbs ft of torque and 50 hp." If I started at 390 hp, that means I'd lose about 80 going from a 10.75 to 9.00 CR. My experience makes me believe Mr. Taylor is correct, all else being equal. That's why I'm still interested in E85, and interested if anyone has tried it in a tri power motor. (The calculator also said I'd lose about 3 hp, which is fantasy IMO.) I think Jim Taylor Engine Service is still in business; I'm going to contact him directly and see if he's changed his belief since he contributed to that story.
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