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New Car, lots of Newb questions

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Proven Member
Jan 12, 2017
Las Vegas, Nevada
Hey there everyone, I'm new here but have been scouring the forums for info for a couple of weeks. I just snagged a gorgeous and very well built 99 GSX but I am looking for answers to a lot of questions that have come up. Luckily, I was put in contact with the mechanic in Phoenix that did all the work and he has been awesome but I want to learn as much as I can and second opinions are usually a good thing. Most importantly I want to keep my car in tip top shape for years to come.

She was built as a weekend racer and has 10:1 high compression pistons. She's only been using above 100 octane but I would like to use it more as a daily, there is a dsmlink ecu installed so I'm assuming tunes should be easy enough. Any opinions on running e85 or some variant with this setup. Or better to run pump gas with less boost as I have read in some posts?

Other specs that may help with answers, 400 LPH fuel pump with 850cc injectors. T-28 Garret Turbo. 2.4L block with a fully built 2.0 head. All sorts of other goodies, I'm very impressed with the work done to be honest but being a new owner I am looking for as much info from the gurus out there as possible.

I'll stop with the craziness for now. Thanks in advance and glad to be apart of this awesome club finally.
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e85 will require larger injectors.

otherwise just have it retuned for whatever flavor of pump gas you can get for your area. you will loose a small amount of power if you retune for 91 octane but i bet you won't notice a difference on the seat dyno.

sounds like an amazing car. why are there no pics?
Thanks for the info, I will look into the re-tune as opposed to running e85. The mechanic who built the car was wanting me to steer clear so I'll take his advice and all of yours. Ironically the weather in Vegas has been crappy since I picked her up and my garage is filled with boxes because I just moved in. As soon as I get a chance to wash and detail the car pics will be obnoxiously present all over the place, LoL.

Thanks again.
10:1 compression seems kinda high for a boosted 4G motor. I bet off boost the pick up is pretty good though. I would personally go for something bigger than a T28 and throw some bigger injectors on there. Why do you want to switch to ethanol though?
10:1 is very high for pump gas, I would recommend using ethanol and upgrading to a larger set of injectors. Your going to be very limited on the amount of boost and timing you can run using pump gas, definitely not it's full potential. Your pump is already big enough, you already have link, if you have access to e85 there's no reason not to use it really.
Thanks again for the responses and the ecm link, I will be scouring that for sure. Let me see if I can answer some of the items brought up and maybe get a better picture of what I need to be doing next week.

The 10:1 compression number comes from the seller and mechanic that built the car. The mechanic isn't a fan of e85, seem blown motors apparently but maybe that was the driver or other issues. I'm fine with it as I have seen so many different suped up cars running it lately, but was listening to him first, hence the pump gas idea.

The other reason for looking at e85 was the octane rating with the high compression the motor has. Basically she's only been run on a mix of c16 and 91 to get over 100 octane from what I've been told so I was looking for an easier way to get to that point as I'd like to drive every day.

I definitely hear you all on the bigger injectors being needed, especially for e85, something to look in to tonight. And it seems like there is e85 all around here in Vegas so that's a bonus.

Another question for you all, if you have an e85 tune and then go for a road trip and get stuck with no e85 around are you screwed? Can you run regular gas and just baby the car until you find e85? Octane booster in the gas a better option? Thanks again.

All I know is I just don't want to hurt my new ride so I appreciate all the help and info very much.
Ecmlink v3 supports the use of a GM flex fuel sensor, when used it will adjust global fuel for you based on the ethanol content of your fuel.
As far as mixing 91 and c16, I don't know how much c16 is, but here in NC ethanol is usually about 12¢ cheaper per gallon than regular gas. Something else to consider.
And it sounds like your mechanic has problems properly tuning for e85. You can't tune an ethanol car off of knock like you can a gas powered car. And if you try, you'll hurt the motor long before any sign of knock. With the proper tuning, no one fuel is more likely to blow your engine than another.
Care to elaborate how it not being 1999 has anything to do with the amount of cylinder pressure it takes to cause detonation. Or as to how time going by is somehow making our cars less susceptible to it. An 8.5:1 motor running more boost and more timing will make more power than a 10:1 motor on the same setup all day everyday. Don't care if it's 1999 or 2999.
So, simplifying down for my newb brain, LOL, for theoretical safety/longevity of the motor but still throw you in the seat punch the options are to

run pump gas with a good tune and lower boost or
snag larger injectors and run e85 with a good tune

Am I on the right track with those thoughts?
Another idea I was just reading about in regards to road trips, (my best friend and his wife live in San Diego so I road trip it out there for beach visits), having multiple maps so you can switch back and forth from pump to e85.

If the dsmlink is already in the car what would i need to switch the maps? Laptop and a special connector? or is there something simpler to just flash back and forth between the tunes? Best bet to go to the dyno and have both tunes done with the larger injectors and then save the maps/tunes and switch on the occasional times I'm not near e85?

Sorry for being a pain in the ass, just want to learn every damn thing I can. Thanks
Some apparently disagree but to reach the full potential of your setup, I would recommend e85, provided you have access to it.
There's a cable included with the ecmlink package that connects your laptop to your obd port. That's how you datalog, change settings and tune.
As far as 2 different tunes for pump and e85, yes that's completely doable. I've heard of people using a toggle switch to switch between the tunes but I'm not familiar with this method. However the flex fuel sensor I mentioned above allows the ecu to automatically change fuel and timing maps based on ethanol content.
For example I have the ecu switch to the minoctane tables whenever ethanol percentage is below 69%. And use the maxoctane tables for anything above. I imagine the toggle switch method is setup similar. Maybe someone else can comment further on that.
Care to elaborate how it not being 1999 has anything to do with the amount of cylinder pressure it takes to cause detonation. Or as to how time going by is somehow making our cars less susceptible to it. An 8.5:1 motor running more boost and more timing will make more power than a 10:1 motor on the same setup all day everyday. Don't care if it's 1999 or 2999.

sure, the type of 'pumpgas' is not the same now as it was when these cars were new. manufactures of all things crude based have been refining and diluting fuel and have come a long way with making it 'better' for them. what that does to the engine though is less power on older cars that do not have the tech in the ECU like todays vehicles. it does make it so we can raise the compression on older vehicles quite safely.

i actually did a huge group of tests on engines and compression ratios in around 2012-2014 (i worked with fuel pump computer systems at the time) turns out on a static timed engine i managed nearly 20:1 compression before detonation was an issue.

the short of it is a turbo motor with 91 octane 'pumpgas' and dsm link 10:1 is not anything to be even mildly concerned about. even a fairly O.K. tune would be good enough.

i also did some testing of different 'brands' of gasoline and all i can say is don't bother driving cross town to get your favorite brand of gas. however i will say there can be some variance from gas station to gas station, some of them are shady and have been caught dumping other stuff in the gas to make more profit (even water).
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^ You are making a very broad and untrue statement. While whatever engine you tested could've very well handled 20:1 compression before detonation on 91 oct, a stock turbo 4g63 would definitely not. If what you were saying were true I could go out and put 91 oct in my car and still run 35psi @ 19 degrees. Octane is a measurement of the anti knock properties of a fuel 91 oct is 91 oct. Lower octane fuel lowers your knock threshold, higher compression lowers the knock threshold even further. And you keep saying ecmlink will make it okay, tuning for pump gas is lower timing and boost and rich afrs. All three of which add up to reduced power.
Anyway this is getting way off topic and I'd like to just help the OP. This compression ratio thing has been covered extensively, by guys who have gone a lot faster than me. compression&page=2
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I suggest you come to Arizona in the summertime and try to tune a 10:1 setup on 91 octane. I then suggest you try a 8:1 setup under the same circumstances. You'll notice you are able to run a lot more boost on the lower compression engine, more than enough to offset the thermal efficiency of the higher compression engine. The lower compression engine will spool the turbo faster, but have much less off boost torque.
Thanks again for all the info everyone. After thinking about everything ad learning more about multiple tunes on the dsmlink I'm leaning towards, new fuel lines, new injectors and an e85 tune to start. Second part will be to do a second tune for 91 octane just in case. So now I've been looking into injectors and have come for more advice...

Any opinions on what would be a better choice? Thanks again in advance, this place is awesome.
I use fic high z 2150s, they are way overkill for a t28 though. I would recommend the high z 1100s should idle great, tune easy and give you a little room for growth.
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