When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
OP: Man I wish we had E85 around me, only issue is the volume required. But mixing it sounds like fun. But now that your mixing it how are you going to monitor A/F ratios? Doesnt ethanol like a different A/F ratio?
Theoretically once I get my VE table dialed in, I should only have to mess with the Stoich AFR(global fuel) depending on the ethanol. For example 9.8~ for E85, 10.7~ for E70 and 11.7~ for E50. Once I get on a dyno I'll see exactly what the combination likes.
What I'm going to start experimenting on low boost 6-8lbs.
E50 Using AFR Gas Scale
Part Throttle lean (max eco) AFR of 14.9-15.9
Part Throttle rich AFR of 13.8-14.8
Spool up... AFR of 12.7-13.7
WOT... AFR of 11.6-12.6
Theoretically once I get my VE table dialed in, I should only have to mess with the Stoich AFR(global fuel) depending on the ethanol. For example 9.8~ for E85, 10.7~ for E70 and 11.7~ for E50. Once I get on a dyno I'll see exactly what the combination likes.
What I'm going to start experimenting on low boost 6-8lbs.
E50 Using AFR Gas Scale
Part Throttle lean (max eco) AFR of 14.9-15.9
Part Throttle rich AFR of 13.8-14.8
Spool up... AFR of 12.7-13.7
WOT... AFR of 11.6-12.6
Any input is appreciated.
Interesting. The E50 should have a richer stoich than all pump gas 87-93. Your saying the WOT for E50 is 11.6-12.6 but you should be in the 11.5-12.0 range for boost, in your application on pump gas. Thus your E50 should probably be a .5 lower than pump correct? So you should be in the 11.0-11.5 WOT or full boost. Then your spool up (heavy throttle building to boost) should be 12-12.5 right?
These number below just seem like regular pump gas numbers, or your saying the first set of numbers is the E50 vs Pump. So WOT for E50 is 11.6 on an NA application and Pump is 12.6 WOT NA which makes perfect sense. So then E50 should be 1 full point richer than gas at all ranges.
E50 Using AFR Gas Scale
Part Throttle lean (max eco) AFR of 14.9-15.9
Part Throttle rich AFR of 13.8-14.8
Spool up... AFR of 12.7-13.7
WOT... AFR of 11.6-12.6
My N/A set up on the dyno tuned for an AFR of 12.5 @WOT on pump gas.
I thought with boost I should be at 11.5-12.0(as you suggested) but at this low boost level the combination seemed to like spooling at the 13~ afr range and leveling to 12.2-12.4 afr at WOT and full boost. I'm guessing it's due to the low boost?
When I changed stoich to E50, spooling AFR was in the low 12 afr range and by WOT it was at 11.4-11.6. There seemed to be a bit of lag vs the 91 gas tune up. At first I thought it was timing so I upped the timing which had little effect. Then I leaned it out to 11.8-12.0 and it responded better. My last pass I was at 12.0-12.2 afr at WOT and it felt better than the 91 tune.
In regards to E85
Originally Posted by stevieturbo
At such low boost pressures, you could safely be running in the 12.x AFR range during spool, and even at 6-7psi I wouldnt be too worried about running 12.0:1 AFR at full boost.
Although once over 5psi, aiming for 11.x will do little harm and always be safe.
E85 high boost(26 psi)
Originally Posted by ForceFed86
If the CC design and compression are similar… A smaller bore engine will need less timing. Flame front has less distance to travel, so it needs less of a head start with spark advance.
Just like any fuel, E85 has a tuning window you don’t want to be out of. E85 happens to have a big window. Peak rich power is around 10.8:1. Peak lean power is around 12.8:1. Unless you have a WB02 on every cylinder It’s better to be on the rich side of peak power to account for some cylinders being leaner than others. Just like timing or anything else… start at a known overly safe rich mixture and lean it out until you stop picking up.
What works for one combo won’t work on another. I ran 10.8:1 AFR on an 8.6:1 SCR 5.3 with LS9 cam. Tried all the way up to 11.8:1 and didn’t pick up any, so I left it rich. Next engine was a 10:1 5.3. It stopped picking up MPH around 11.4:1. So that’s where I ran it.
Back pressure and the cam will have a lot to do with where peak torque timing is on any fuel. My 10:1 E85 5.3 with a low duration cam (212/212) @ 26psi ran great at 15*. Went to 17* blew the HG 3 passes later. Other combinations run 20-30* of peak timing at similar boost. Again… Only way to do it safe is to start low and work your way up watching plugs and power/mph.
My N/A set up on the dyno tuned for an AFR of 12.5 @WOT on pump gas.
I thought with boost I should be at 11.5-12.0(as you suggested) but at this low boost level the combination seemed to like spooling at the 13~ afr range and leveling to 12.2-12.4 afr at WOT and full boost. I'm guessing it's due to the low boost?
When I changed stoich to E50, spooling AFR was in the low 12 afr range and by WOT it was at 11.4-11.6. There seemed to be a bit of lag vs the 91 gas tune up. At first I thought it was timing so I upped the timing which had little effect. Then I leaned it out to 11.8-12.0 and it responded better. My last pass I was at 12.0-12.2 afr at WOT and it felt better than the 91 tune.
In regards to E85
E85 high boost(26 psi)
well thats the thing. 11.5 is safe for a 6+psi boost. 12:1 is fine at lower boost and thats why it has the range of 11.5 - 12.0. Any time you add positive pressure your AFR should reflect that due to the added air+added fuel = more hp. The added fuel can help with charge cooling and lowering combustion temps.
I have personally been to 12:1 on my 12psi 93 pump gas 5.3 and it didnt damage anything but I run a FMIC and water/meth.
E50 would have better cooling charge capabilities over pump gas but not as much as E85... which would mean you could run more timing like water/meth allows for detonation control.
Every engine wants something different but I would error on the safe side. Too rich can be just as bad as too lean, Ive gotten the overly rich bog at like 10:1 or where it started to feel like turd on its way during tuning. Leaning out is ok as long as you dont go too lean. Boost and lean will cost you pistons and possibly heads.
You're right. I think I'll go a little richer before I put it on the dyno and find out exactly what it likes.
My next area is timing on E50. When running 91 octane and low boost(3-4psi), I was running real conservative timing, 14 degrees at wot(removed 12 degreees from NA tune). Need to figure out how much timing to add for the E50 and how much to remove per lbs of boost.
This is my NA 91 pump gas spark table.
For 6-8 psi on E50 I'm thinking off adding 4 more degrees at WOT but not sure where else to add timing.
The fact that you're pulling from the top of the tank could be contributing to your problem. Most pumps push better than they draft. If your going to do an external pump, a sump is your best bet IMO.
Put another 255 pump into the tank and wire that up then you'll be good. If your running a holley efi system on your 3rd Gen like I am your computer can trigger the second pump at whatever boost level you want.
Wait I thought u were running a single intank 255!? If that's the case u def are around its limit. Not to mention your boost if your using a boost reference regulator adds 1psi per psi of boost. Pumps pressure increases and your pumps output decreases.
At minimum you need a 340 or a 450. Dual 255s is another option. Easiest way is to run around on one 255 and then trigger the 2nd with a $20-30 Hobbs switch.
I just did my walbro 450 swap Sunday. God I hate pulling that damn tank and the back half of the car. Make sure you pick up submersible fuel line to connect it. The install kit for the 450 basically comes with nothing but wiring harness and pigtails and a filter. U need the tank oring and submersable
hose and large stainless clamps to clamp the pump down... well at least in the stock 3rd gen tank for me.
Video looked good!
Timing your wayyy higher than mine. I'm running 18-20 degrees at WOT but my timing is lower around the mid range compared to yours. Gotta see if I can fire up my laptop and get a screen shot for you. Plus I'm on 93 and 50/50 water meth but I'm at 12psi. You need more timing but your WOT is not 14* it's showing like 26 according to your pic.
The fact that you're pulling from the top of the tank could be contributing to your problem. Most pumps push better than they draft. If your going to do an external pump, a sump is your best bet IMO.
Originally Posted by 91 Z28
Put another 255 pump into the tank and wire that up then you'll be good. If your running a holley efi system on your 3rd Gen like I am your computer can trigger the second pump at whatever boost level you want.
I have a walbro 450. Trying to decide if it will be enough by itself or if I should run it in addition to the 255 controlled by a hobb switch. That plus how to plumb the return line.
Originally Posted by customblackbird
Wait I thought u were running a single intank 255!? If that's the case u def are around its limit. Not to mention your boost if your using a boost reference regulator adds 1psi per psi of boost. Pumps pressure increases and your pumps output decreases.
At minimum you need a 340 or a 450. Dual 255s is another option. Easiest way is to run around on one 255 and then trigger the 2nd with a $20-30 Hobbs switch.
I just did my walbro 450 swap Sunday. God I hate pulling that damn tank and the back half of the car. Make sure you pick up submersible fuel line to connect it. The install kit for the 450 basically comes with nothing but wiring harness and pigtails and a filter. U need the tank oring and submersable
hose and large stainless clamps to clamp the pump down... well at least in the stock 3rd gen tank for me.
Video looked good!
Timing your wayyy higher than mine. I'm running 18-20 degrees at WOT but my timing is lower around the mid range compared to yours. Gotta see if I can fire up my laptop and get a screen shot for you. Plus I'm on 93 and 50/50 water meth but I'm at 12psi. You need more timing but your WOT is not 14* it's showing like 26 according to your pic.
Yeah I'm going to get the accordion style hose(ethanol compatible) from racetronix. I'm running the 4th gen tank and already modified the bucket when I installed the walbro now I need to figure out how in depth I want to upgrade the fuel system(fpr, fuel rails, 8an lines, return, etc.).
The timing table above was when I made 400rwhp on the dyno all motor. I trimmed the timing down significantly when I first got it running but now on E50 this is what I have in there.
Picked up a stock evap line that I'll be using for return along with a FPR and fittings.
Meanwhile been driving the car on low boost logging some miles. Noticed discrepancies when building boost so I bought a $5 coupler added a valve and hooked up my 12v compressor.
Just a thought but I have a ported throttle body and it also has a hole on the throttle blade.I know some cars/trucks guys would drill holes to get a min idle on ported throttle bodies.i bought mine used and never went back to stock.i cant exactly pressure test my system this way. Also are you sure the set screw on the throttle body isnt set too high creating a slight opening on the blade itself?
Having just had my TB apart. There are also no real seals on the throttle shaft. On the TPS end the sensor has a seal but on the cable end there is no seal in the housing. The shaft is just bar and it fits In the hole.
I also have holes in both my TBs that were stock. Seems like air is working its way through on a area where the shaft is worn. Or more air is being let in the motor as you open the blades and leak through on the motor. Pistons have a leak down so the engine isn't air tight.
Food for thought, one of the BOVs leaks constantly but it doesn't really affect boost. That leak is so minor I doubt it's causing any issues.
Just a thought but I have a ported throttle body and it also has a hole on the throttle blade.I know some cars/trucks guys would drill holes to get a min idle on ported throttle bodies.i bought mine used and never went back to stock.i cant exactly pressure test my system this way. Also are you sure the set screw on the throttle body isnt set too high creating a slight opening on the blade itself?
Originally Posted by customblackbird
Having just had my TB apart. There are also no real seals on the throttle shaft. On the TPS end the sensor has a seal but on the cable end there is no seal in the housing. The shaft is just bar and it fits In the hole.
I also have holes in both my TBs that were stock. Seems like air is working its way through on a area where the shaft is worn. Or more air is being let in the motor as you open the blades and leak through on the motor. Pistons have a leak down so the engine isn't air tight.
Food for thought, one of the BOVs leaks constantly but it doesn't really affect boost. That leak is so minor I doubt it's causing any issues.
Thing is when I first started data-logging, the car would build boost instantly despite being pig rich and super safe timing on 91 octane. From vacuum to 3.8 psi progressively.
After my last pulls on 91 octane I began to have weird idle issues(might have blown the tb shaft seal?). I switched to E50, re-tuned idle but spool was odd, it would hang up at 1.5 psi then spike to 3.8 psi. No longer progressive. I want to eliminate leaks before I up the wastegate spring. Luckily none of the silicon hoses were leaking
Also found this regarding boost leak from the same area:
Originally Posted by User-c3
I took the throttle body apart, and removed the rubber seal that the throttle shaft slides into. The way the seal is made makes sense for a naturally aspirated engine because it keeps the seal tight under vacume. unfortunatly under positive pressure the seal just lets air out because its not strong enough.
Here is a model I did to show the seal. I didnt take a picture of the factory seal so this will be a good representaion.
You can see how the sealing portion of rubber is bubbled outboard.
When on the shaft and under pressure this flap type rubber seal just spreads and lets air out
By flipping the seal it acts in a reverse idea. Under pressure the seal flap becomes pressed outboard and in tern making the seal tighter.
In addition to flipping the seal I added an O-ring that fit inside this flair type of indention to strengthen it.
I then added another smaller O-ring on top of that one that added another place of sealing.
I also added the same size O-ring on the opposite side creating 3 points of contact aiding in the sealing.
I then put the seal back in the throttle body reverse of the factory position and sealed it in with rtv silicone. The seal doesnt exactly fit tight reversed so the silicone is important to seal the outsides.
I let it dry over night before I reasembled the throttle body
Thats a new one i havent heard about on the tb shaft seal.Though i do question just how much this actually makes a difference because at idle your not going to be in boost and the tb blade is closed.At wot..would this really be a point of concern? I doubt it imo but ya never know..just curious.
Interesting. Didn't even see the seal when I had mine apart. Wondering if mine even had it honestly. Going to have to see if I have one on mine ugh.
I doubt this is your irratic boost issue. I honestly think it's a sensor thing. You should put a volt meter on the MAP sensor and key on and manually very voltage readings at various vacuum and boost pressures. I got some very wonky readings when I was testing a cheap MAP sensor. Could be a faulty or loose connection etc.
Another option is buy sealed bearings and put in the throttle body... They have seals both directions. You might have to machine the hole in the throttle body but a bearing specialty house should be able to set you up.. I used to do this on blow through webbers many many years ago... They were notorious for the throttle shaft wearing out the carb and putting brass bushings in was the common fix but the bearings made the throttle so buttery smooth and easier to move..
Thats a new one i havent heard about on the tb shaft seal.Though i do question just how much this actually makes a difference because at idle your not going to be in boost and the tb blade is closed.At wot..would this really be a point of concern? I doubt it imo but ya never know..just curious.
Not sure it'll matter when I turn up the boost but I'll rig something up just to rule it out. This was with about 5 lbs of pressure, I imagine it would get worse at higher levels?
Originally Posted by customblackbird
I doubt this is your irratic boost issue. I honestly think it's a sensor thing. You should put a volt meter on the MAP sensor and key on and manually very voltage readings at various vacuum and boost pressures. I got some very wonky readings when I was testing a cheap MAP sensor. Could be a faulty or loose connection etc.
I'll put that on that on the to do list.
Originally Posted by pdxmotorhead
Another option is buy sealed bearings and put in the throttle body... They have seals both directions. You might have to machine the hole in the throttle body but a bearing specialty house should be able to set you up.. I used to do this on blow through webbers many many years ago... They were notorious for the throttle shaft wearing out the carb and putting brass bushings in was the common fix but the bearings made the throttle so buttery smooth and easier to move..
thanks that would be an ideal fix!!!
Aeromotive clone came in. Hope it doesn't leak wish me luck.
02-17-2017, 12:34 AM
