LSs1Power

iTrader: (5)

I was thinking if there is a relationship between those three. I'm asking because Im getting a D-1SC very soon and i want to setup the car for road course racing without blowing up my motor due to high IAT or high EGT which could cause detonation from what i understand soo far. I was wondering if i need to watch my IAT or EGT or both of them after 20min of hard driving. What do u think guys?

NoGo

iTrader: (2)

Just keep your knock sensors and get an onboard a/f meter.

QuickSilver2002

EGT will give you some indication of A/F, but it is not that intresting on a supercharged car. Turbos are where EGT is more important.

A good scanner like EFI-Live is a good place to start. It will log most of what you need.

LSs1Power

iTrader: (5)

I have EFI V5 Live and it gives me the IAT, but i wanted to know if there is a relationship between IAT and Detonation. I heard that detonation could be caused by high IAT even if u have enough fuel and the car is tuned right. That is why i wanted to confirm this piece of information. At what temp (IAT) do i have to start worrying about detonation if there is a relationship between the two? Im going to get a really good wideband A/F ratio gauge from this site http://www.plxdevices.com/products.htm

QuickSilver2002

Yes there is a relationship between IAT and detonation. This is why there is a table in the PCM where you can reduce timing based on IAT.

The relationship is there but there is no magic formula (like x IAT = detonation). You will just have to learn what your particular setup likes and dislikes. Detonation thresholds depend on so many things that you just have to experiment under different conditions (weather, fuel, load, boost) The knock sensors help out quite a bit here. You can monitor KR with EFI-Live and you should be able to see where it starts to see lite pre ignition. You then have to add more fuel, back down the timing, lower the boost, improve the intercooling, run better fuel, or simply back off the throttle. Think of it as a balancing act. Some people run leaner a/f with less timing, while others will run rich a/f with more timing. It's all about trying to controlling heat and pressure in the combustion chamber (IAT is just one factor in that equation).

LSs1Power

iTrader: (5)

Sounds like i need to have my laptop in my view when im on the road course then. Its going to be intresting driving and monitring the screen LOL. Anyone know when better intercoolers are needed? For example if the weather out side is 90F and the IAT started at 110F and after 20min of hard driving it went up to 170F.... Is this good or bad and when do we know that we need a better intercooler?


Thanks for the useful info.

NoGo

iTrader: (2)

There is no specific IAT that is going to cause detonation. There are alot of factors to consider.

1) How sensitive is your car to detonation
2) Gas Quality / Octane
3) Boost Level
4) Intercooler Efficiency
5) Load on Engine

You don't have to drive and monitor your screen. Put a good conservitive tune in the thing (a/f around 11:1 ON THE STREET, timing in the low 20's) run an octane booster (or race gas) and you will be fine.

The biggest thing you should be worrying about when deciding to road race a FI is getting your fuel system up to spec. Ensure that you have the proper size fuel rails, pump, and injectors. More RR cars kill #7 because of improper fuel damping, too small rails, or injectors.

Additionally, if you are going to run a usual supercharger kit, you are going to have to either run an air/oil separator on the crankcase vent system or diconnect it entirely. The high RPM's coming into the corners will cause your motor to burp all kind of oil into your inlet hat of the supercharger. The extra oil getting into the motor could cause it to ping like crazy.

Good Luck

LSs1Power

iTrader: (5)

The SC is going to be ATI D-1SC with the twin intercoolers.
1) How can i tell? It never detonated until now.
2) 94 Sunoco Gas
3) 8 psi on stock engine, thinking of 10psi on 104 octane.
4) Im really not sure how efficient the twin intercoolers are? Do u know?
5) How can i measure the load on the engine? I have seen in EFI live something aboit load, but what numbers i should be looking for?

Do u kow if i need to run an air/oil separator on the crankcase on a procharged car since the oiling is externally?


Thanks for the info guys

QuickSilver2002

Yep, this caused me major problems. I had to disconnect it and vent to atmosphere. Going to the ls6 style PCV will help in the corners... but you still have vapor issues to deal with from blowby.

LSs1Power

iTrader: (5)

Which SC do u have?

NoGo

iTrader: (2)

Firstly, valve springs: I had one let go my first year of RR. I was lucky and nothing else got damged (the spring bound when it broke), but I learned an important lesson. If you are going to spin the snot out of your stock car ensure that your valvetrain is up to the task.

If you are going to be running 10psi on the D1 on a road coarse then you really need to consider a spring belt tensioner for your blower. The belt heat/expansion/wear that occurs while road racing can cause your blower to start slipping once everything gets warmed up.

I'm not a big fan of the ATI setup for the F-bods. The intercooler setup does not allow for much 'intercooling'. If you are considering RR you may want to address this point. Either add some additional ducting, clear a path for the air, etc...

You can't tell how sensitive your car is to detonation until you get the blower hooked up.

Again, I would just get a good tune in the car. Park the a/f around 11:1 and set the timing conservative. If you are really worried about detonation, they have gizmos that plug into your KR. When the knock sensor pick up KR a light lights up on your dash.

Good Luck

QuickSilver2002

I've been looking for something like this. Does it really work with an ls1? Where can you get it? I thought all the actual intelligence of the knock detection was somewhere in the PCM and it would be impossible to hook into without tapping into the diagnostic network.

LSs1Power

iTrader: (5)

Thanks for the advice.... I have 26918's already so im ok there. I will make sure to tune the car at 11.1 AF. Is it a good idea to have strong fans behind the intercoolers to pull more air at any speed? From where can i get the sping belt tensionor?

Pro Stock John

iTrader: (34)

Great advice from Kevin, I would absolutely do valve springs.

You might want to also look into some of the nitrous threads discussing LS1 Edit tuning for high IAT readings... you could have the pcm pull a lot of tuning when it gets too hot...