I currently have a C7z making around 730 whp on 93 and I was looking to run full e85 (my tuner won't tune for a mix, just straight E), whatever the pump currently has (probably closer to e70 or so) and a little more boost. I was really looking to get around the 800-850whp level. I was curious if anyone out there could tell me what fuel system mods I would need. Current mods are DSX low side fuel system and a BTR stage 2 cam with 38% fuel lobe to the stock lt4 injectors and hpfp. I am currently making about 730 whp on 12.5 psi (93 octane) with a Maggie 2650 with the 90mm upper and 15% OD lower and was looking to bump boost to about 15 psi with a 18% lower and 85mm upper. Also have a 103mm TB, CPR 5" CAI, and ARH 1 7/8 LT headers. I've done a little looking around and it seems that +30% DI injectors alone should allow me to support full E on this setup, but I want to get some other input as I would prefer to only remove the supercharger once. I am not interested in going past this level on the stock bottom end, so I don't want to replace anything extra if its not needed and would prefer to stay away from SPI as it would not really be worth it as I am not really planning on pushing for huge power in the near future. I would also like to stay away from meth as I don't really like the idea of relying on the single meth pump to be supplying extra fuel. Basically I'm wondering what others have done to get this power level and if it may be possible to get away with it with just an injector upgrade or if it is completely necessary to get a hpfp too (LPE?). Any input on what fuel system changes you guys made to reach 800-850 whp would be greatly appreciated! Thanks

 

think long and hard before you tune for straight e85 versus a flex map. e85 in the US can be between 51% and 83% ethanol, legally. it also has varying levels of availability.

it's a (imho giant) red flag that your tuner won't do a flex tune for you. It's as simple as doing an e85 tune against a known quantity of ethanol and using a trim map based on the flex sensor.

 

basically you have 2 ways to go
1. 65% upgraded dfi I vectors and a big bore pump
2. port in section with a ecu to run the added 8 in sectors and size you choose. typically a 1050 or 1300 cc injector

 

I think what my tuner meant by straight e was to have the fuel system to run straight e85 with the flex sensor. What I took from him was that he didn’t want to mix x amount of e85 and y amount of 93. He wanted to tune the car with the fuel system to be able to run straight pump E. I would personally not mind running a blend as the benefits of full E85 seem to drop rapidly after about E40-E50 or so.

 

Thanks for the reply! I would really need SPI or a pump and 65% injectors for only 800-850 on E?? I thought XDI’s website said +30% would be able to handle e around that power level. They must be wrong then, that’s why I like to get experience and advice from people who have been down the road before.

 

That makes more sense. I am thinking about supercharging my Z51 next year. I already have a flex sensor and E85 tune and would like to keep the ability to run E85 when I do supercharge the car. I'll have to do low side, injectors and high side pumps at minimum. I plan to stay under 650 whp on a stock LT1 short block so am hoping just the DSX low side and LT4 pump and injectors will be good enough for full E.

I do not want to mix and keep track of that. We have stations in my area that all test E75 or higher.

Hopefully, some more knowledgeable folks chime in with what the max power level vs mods equates to for running full E.

 

Right, so the tune itself is done on the highest concentration of ethanol you can get. From there it's practically zero effort to enable flex for any blend up to what was tuned.

 

what you were asking was what was needed to be able to run full pump e85 (around d me most stations are e70) . thats what my reply was based on. xdi 30% injectors will allow a blend of ethanol but doubtful you can run full e85 and lose pressure at the high side under wot

 

I think you would need a cam with at least a 32% fuel lobe in combination with all of the fuel mods yo stated to run full E85 at that level from what I have seen and have found.

 

Yeah I think I'm going to have to do more than just the injectors. Thanks for the input and help. Only reason I thought I might be able to get aways with it was because of what was mentioned on XDI's website and I saw a thread on the camaro6 forum and someone had about the same mods as me explained that the pump still had pressure but the injectors were running too low. Guess I am gonna have to reassess lol.

 

Already have it. Cam/ported heads/ported intake and TB/LT headers/CAI/E85.

 

Keep me updated and let me know how it goes when you end up installing the supercharger.

 

Take a look at my setup in my signature. It seems to be near what you're aiming for. Here in Houston at sea level I was at about 15-16psi with a 90mm upper/ 9.06 (12%) lower.

With only the DSX low side I maxed out at 705 on 93 octane. With the cam and methanol I was able to get to low-mid 900s on 93 octane. The highest ethanol mix I could run was about e50 before lowside dropped too much. My suggestion is to go port injection. The toohighpsi kit is a little under 3k for their strongest fueling setup. That will allow you to run full E85 assuming your lowside can handle it.

Also why won't your tuner do a mix? There are some great benefits to be had with a mix.

Methanol isn't an issue. I have ran it for 2 years with 20k miles. It can be a small hassle though.
If I had to do it over I would've just done port injection first thing. It's just the best fueling method for these cars.

 

Your correct, 30% injectors and the Lingenfelter Big Bore is enough bassed on the current nmods.. Were at 875 rwhp 100% E85.. Now, that is if you have the proper tuner..That is everything.

 

Tuner wont tune for a mix of E? I'd get a new tuner. Pump E is not always the same %. You need to tune for flex fuel so that the ECU adjust for the ethanol percentage, which changes at the pump.

 

What low side and other mods are you running? I think I would like to do a setup similar to yours

 

Thanks for the info. If I can't find a way to run the full e85 that is practical for the power that I'm shooting for currently, I think I may go with a route similar to how you went.

 

i just went through all of this so i'll chime in also. my low side is a custom 400lph aem pump feeding, lpe bb hpfp and xdi 30% with LPE gt35 cam shaft, afe intake (stock TB and SC inlet). 15% lower with 90mm upper 2" catless headers with x pipe. max boost was 16psi averaging 15psi. injectors maxed out at e65. our pump e here in BC canada is e60. so we are pretty much at the limit of IPW (tiny bit of room left). car made 830whp and 773wtq e60 (flex tuned). you have to check the injector max operating pressures because the stock LT4 pump operates much higher then the BB. (set to 2500psi) Note low pressure fueling was strong and doesn't drop at all. Id recommend LPE BB and 65% injectors if your going the DI route. right now as it stands if i want to make more boost i need to go with 65% injectors.
i too was adamant on not running meth and do not want to mix e as its a pain in the butt.

LMR just did a build that made 900whp with just aux low side and DI upgrades on full e for reference.

 

Thanks for the input! I definitely think that I'm going to go this route as doing more research I don't love the idea of another computer controlling the port injection and meth always seems like a big risk to me even though many have used it and been just fine. Awesome you can get away with 15 psi on that pulley combo, I am running the same combo and only make like 12/12.5 psi. Im going to an 18% lower and 85mm upper to hopefully get around 15 psi and then I'm going to assess my situation from there. I'm trying to find the best way to reach around 850 whp until I decide to go to a 427 ci motor, so I think upgrading the DI is probably the way to go. Thanks again for sharing, I appreciate it.

 

Actually tuning the Too High PSI system is pretty straightforward. The latest versions have closed loop at WOT so that you will always attempt to hit your PE target so that you don't have to adjust for weather changes. I too chose to remain DI only on my personal car and paid the costly upgrades for the aftermarket DI stuff. Although I did it before the last price hike which makes the parts about $2200 more than they were a year ago. If you have a cam, LPE BB and 65% injectors, you can take the DI system pretty far on E70.