LT1-LT4 Modifications 1993-97 Gen II Small Block V8

E85 Tuning Tips

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Old 09-01-2010, 09:57 PM
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I think the Autolite 104's will be fine, here are pics of 2 of them (#6 and 8, others all look the same:




The best size injectors for my setup would have been 50#, as I am at 66-68% DC at 6300 RPM on the 60#'s. However, I got a better deal on the 60#'s than the 50's, so that's what I went with.
Old 09-01-2010, 10:25 PM
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Wicked94Z, here is my extended timing table from TunerCat, I added 1* across the table upon getting the mail order tune by MadZ28.com for my 226/226 .582/.582 110LSA cam degreed to 108 (via cam card spec). However in DataMaster, it shows my timing going as high as 40* at 5500+ RPM. This seems a little high for my cam, right? Why does DataMaster show higher than TunerCat?

Last edited by kgkern01; 09-01-2010 at 10:34 PM.
Old 09-01-2010, 10:52 PM
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Because the LT1 PCM has a built in advance. 3 degrees at WOT in my experience.
Old 09-01-2010, 11:01 PM
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I've never gotten a clear response on the timing variation, except one guy that said the LT1 PCM adds 2 degrees ~2500rpm, and another 2 degrees at ~4500rpm. All I know is you should tune according to datamaster. Without going cell by cell... at 45-100 kpa i'd take 4 degrees out of it. 6 degrees from 35-40. and 3 degrees from 30. I really don't see the need for so much timing with small chamber lt1 heads. If you post up your .bin I'll do the timing tables how they were on my setup just so you can take a look. Obviously I was running like 32 degrees advance at idle because of the big cam so my tables below 2000 rpm might be a little radical for your setup.
Old 09-02-2010, 08:55 AM
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Default E85

Here is an estimate on A/F Gas vs E85 tables.

Air/Fuel Ratios


Fuel Stoich Rich Limit Lean Limit
Gasoline 14.7.1 12.5.1 13.2.1
Methanol 6.4.1 5.4.1 5.7.1
Ethanol 9.0.1 6.4.1 7.8.1
E-85 9.7.1 6.9.1 8.4.1


FORCED INDUCTION OR NITROUS APPLICATIONS

Fuel Stoich Rich Limit Lean Limit
Gasoline 14.7.1 11.5.1 12.2.1
Methanol 6.4.1 4.4.1 4.7.1
Ethanol 9.0.1 5.4.1 6.8.1
E-85 9.7.1 5.9.1 7.4.1

Fuel Stoich Rich Limit Lean Limit
Gasoline 14.7.1 10.5.1 11.2.1
Methanol 6.4.1 3.4.1 3.7.1
Ethanol 9.0.1 4.4.1 5.8.1
E-85 9.7.1 4.9.1 6.4.1
Old 09-02-2010, 09:46 AM
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I'll back the timing off 2* first and 3* in the 35-40 and see how it runs with that first.

As far as the A/F, I know what that is supposed to be, and my WOT A/F is pretty steady at .79 lambda or 7.72 E85 ratio, reading 11.7 on a gasoline display.
Old 09-02-2010, 10:07 AM
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Instead of going by an arbitrary timing number, read the timing marks on your plugs and see what or setup actually likes IMO..
Old 09-08-2010, 06:37 PM
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I have always read that E85 likes a little more timing than gas, is this not true?
Old 09-08-2010, 08:55 PM
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In general yes but reading the plugs is the best way to find the optimum amount of advance for a given fuel, combination etc
Old 09-08-2010, 08:59 PM
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good luck reading plugs for part throttle driving 30 degrees is a good conservative number to start with at WOT and he can increase from there for max power/mph or whatever.
Old 09-08-2010, 09:05 PM
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Originally Posted by kgkern01
I'll back the timing off 2* first and 3* in the 35-40 and see how it runs with that first.

As far as the A/F, I know what that is supposed to be, and my WOT A/F is pretty steady at .79 lambda or 7.72 E85 ratio, reading 11.7 on a gasoline display.
you don't need that much timing part throttle! I don't know what size cam you're running, but i doubt you'll ever see 35-40 kPa. I was cruising at like 60+ with my old setup. I wouldn't put more than 40 deg ANYWHERE in your spark tables, it's just not necessary. Every timing table I've seen on this site has had WAY too much advance everywhere.
Old 09-08-2010, 09:08 PM
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True. I was referring to wot. Part throttle I would street tune based on feel, responsiveness, etc and the absence of knock. You have to even be careful with that though, I've "heard" you can push E85 hard enough to cause damage even with no indicated knock retard.
Old 09-08-2010, 09:13 PM
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yea i knew what you meant, just trying to clarify for the OP. you are definitely correct about E85 not audibly "knocking" but still causing damage. That's why you should start conservative, especially without knock sensors (me), loud exhaust/ttops (fastfatboy), etc.
Old 08-31-2015, 11:47 PM
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Originally Posted by gregrob
True. I was referring to wot. Part throttle I would street tune based on feel, responsiveness, etc and the absence of knock. You have to even be careful with that though, I've "heard" you can push E85 hard enough to cause damage even with no indicated knock retard.
hey dude have a few questions can figure out what injectors to run with my build i plan on running e85 with atleast a 200 shot. i got 12:1 compression. i was thinking 50s or 60s would that be too much? or settle with 42s?



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