N/A efi Motor running E85 with Nitrous

Good day/Evening all,

Im hoping some of you may be able to assist me in any knowledge or experience on the topic above 'N/A efi motor using E85 fuel with Nitrous'.

I drag race a 1965 VW Beetle here in the UK and was previously running my 2276cc flat four motor on Renegade NOS Pro + fuel with a 140 shot of nitrous and managed to run a 10.49 @ 125 mph on the quarter mile.

Moving onto 2021 prep i am looking at going down the road of using E85 with nitrous on my set up which uses a DTA S40 ECU and complete Nitrous set up with full logging capabilities on the engine itself.

My reason for the post is there's little to no experience in the UK doing this that i know off and using drag racing linked pages on facebook etc to gain any information like jetting, timing etc has been mixed so far.

You maybe wonder why i'm thinking of the switch, but i think with the cooling effect E85 has i may keep the heat down a little to allow us you use bigger shots of nitrous but not be as hard on the motor as if i was running race fuel.

I have a really good tuner who will be mapping the cars, who has experience with E85 but mostly turbo set ups, but im trying to be proactive and learn what i can ready for the move and future adjustments at the track when i change the shot size.

Many thanks for your time,

Clarkey

Hello Clarkey,

you're correct in that its not a common application but I'm sure someone has covered this elsewhere in the world. It could also be worth looking at time attack cars as a number of them run E85 and nitrous, off the top of my head locally I think the RCM Gobstopper 2 may have so it could be worth a phone call.

I would suggest approaching this by tuning the fuel/ignition on E85 first then adding in the nitrous and finessing the calibration from there. This would mean you have a known base to work from and a known next step in adding in the nitrous.

You will have to add fuel for E85 and depending if you engine is knock limited increase ignition advance.

The charge cooling effects of ethanol will be negated by using nitrous which in itself reduces charge temps further, ethanol will however have some effect on EGT due to its' stoichiometry and the requirement to run richer but again this may be mitigated by increasing ignition advance.

The flex fuelling course may cover some of what you need.

https://www.hpacademy.com/dashboard/courses/ethanol-and-flex-fuel-tuning

There are a number of SAE papers that investigate E85 and temperature, this is an example of one.

https://www.sae.org/publications/technical-papers/content/2007-01-1392/

There does seem to be a fair bit of discussion on-line about NO2 and aircooled VW engines - try a few different search terms.

Both the E85 and NO2 will lower charge temperatures, but the combustion temperature change, if any, will depend on the balance you go for. I did some checking a while back about the evaporative affects of alcohol fuels against petroleam base ones, if I recollect correctly, the differences were negligible, but there.

Not sure why you think it's going to be less hard on the engine, as that's going to depend on the tune, and both how much gas and WHEN it's used. I would emphasis the "when" because as it is a fixed amount of power, regardless of rpm - the lower the rpm it's used the greater the additional torque and hence loads on all the engine and transmission components. A "100 shot" at 7k rpm will be an additional ~75 lbs.ft, but at 3500 it will be ~150lbs.ft, with the associated, much higher, cylinder pressures.

Something to be aware of, if it's a drag only engine, the ring gaps may be a little tight for the gas, something to check on, and correct if required, before leaning on it.

Sounds like a fun little car, got a bit of a soft spot for the older Beetles.