Please coach a newbie

Alright, I've got an 82 Datsun 280zx; N/A converted to turbo with megasquirt, larger injectors, etc. 5 psi boost, no intercooler. There's an autocross in CT on 8/8. I'd love to attend.

But:

1) I don't have a helmet. No loaners available. They require SA, not M. Is there a reason to buy open faced versus closed?

2) I get some pinging when its hot out under boost occasionally. I'm worried I'll blow the headgasket at the autocross, and its a 2 hour drive home. Can anybody recommend an octane booster? Grassroots chemicals or an Autozone off the shelf...?

3) I have T-tops. Problem?

4) What class (besides novice) should I expect to run in?

Thank you!!

A lot of larger events, HPDE's, LeMons, Chumpcar are going to require a full face helmet. Might as well buy one if you plan on doing more than one autocross, ever.

As far as octane booster.... toulene. I don't remember what the exact mix is (It's been a while since I've done that) but I want to say it's something like half toulene, half 93, and you get 110, or thereabouts.

Who is putting on this autocross? Most clubs in the area allow M helmets (and have loaners). I prefer open faced helmets for autocross, but full face helmets for the track.

Address the ping first.

Oh, and the ping? Yeah... you want an intercooler. That'll likely solve most, if not all of your problem. Either that, or perhaps consider meth injection.

Wow that was quick!

Autocross is put on by CART. I'm not a member but our z-car club is invited to this event. Its funny, the CART site says M is OK, but the coordinator within our club says SA no exceptions. If I'm going to buy one, I'd like it to last for a little while. Autocross - wish I could find more locally. HPDE - yes, at some point next summer.

Ping - I just haven't had the time to add an intercooler. Its on my list of things to do, but it won't be done before 8/8 for sure.

mikeatrpi wrote: Alright, I've got an 82 Datsun 280zx; N/A converted to turbo with megasquirt, larger injectors, etc. 5 psi boost, no intercooler. 3) I have T-tops. Problem? 4) What class (besides novice) should I expect to run in? Thank you!!

T-tops: Not a problem. You can run with them in or with them out. Most people take them out. You are not allowed to use an aftermarket upper body restraint like a harness or torso strap if the tops are off according to SCCA rules. Are you running an SCCA event?

Class: due to the turbo convert and the megasquirt you will likely be placed in a Modified Class. This will put you up against tough competitors but do not worry about that. Make your runs for your own improvement and judge yourself against the entire field of competitors.

Ive seen people freeze down intake manifolds with a lump of dry ice before running drags to cool intake air temps, perhaps you can do this prior to a run? what about retarding your timing a tic? Some sunocco stations around here (SW Ohio) will carry 94 octane fuel, and real 100+ race fuel is out there too, speed shops typically can tell you where to get it.

as far as ping, run less timing as 4cylindrfury pointed out unless you can get high test either is the quick fix, but I wouldn't rely on it to 'correct' the underlying problem.

If you have larger injectors have you not tuned your MS for the boost? Have you calculated your duty cycle? what's your fuel pressure? maybe adjustable fuel pressure regulator if you're pegged on duty cycle at 5psi? Just worry about locking the injectors. Honestly with MS and larger injectors and such minimal boost I'm failing to see how to correct the issue here. Are you running MAP or something else?

what are the requirements for a helmet for HPDE and NASA? I was going to get one but I couldn't find what safety specs it had to be.

An intercooler will handle your pinging problem I'll bet. But, it sounds like you're under a time constraint here. I'd recommend the octane booster and pull the timing while under boost. It's not hard to do that with MS's timing tables. That should take care of your issues for your to run your autocross.

If CART is running the event, their rules apply,not your club. Contact CART directly. As long as you have to buy a helmet go with a full face SA . Then you will be legal wherever you go. Is there a race shop near by that sells racing fuel ? Another posibility.

Another thing. If you go full face, get one with a large eye opening. I like the Simpson Voyager for this.

Just turn the boost down a little for this event. The loss of power won't make any difference until you get some seat time.

The best thing about buying the helmert is that you can get one that fits well. Comfortable, but snug.

I'd cure the pinging by tuning the ECU properly. That's why you have a programmable ECU. It's the best choice. Pinging/detonation may not cost you a head gasket, it might take out the bottom end.

As for grassroots octane, toluene. It's around 110 octane, and the math is a simple average of the octanes of the two fuels involved. ie 5 gallons of 90 octane and 1 gallon of 110 gives 6 gallons of 93. I wouldn't go more than about 15% though, it can be hard on fuel components. This is the hack bandaid solution that you use when you discover you have bad gas or a tuning problem at the track, the correct solution is to fix the tune.

CART usually has loaner helmets.

Ask Car39. He should know.

Or, look here:

http://www.cartct.com/index1.shtml

I had thought my timing was pretty conservative. It feels a little sluggish and definitely smells rich, but runs reliably. My plan was to add the intercooler, up the boost to 7psi, and fix my tune.

Now they're dangling the autox carrot in front of me and I want to participate without blowing anything up.

I don't expect MS advice, but I'll still post my maps if anyone is curious.

By the way - I forgot to say Thank You in the last post. I do appreciate all the tips! I've auto-x'ed before but never in my own car... its time to try, right?

jonnyd330 wrote: what are the requirements for a helmet for HPDE and NASA? I was going to get one but I couldn't find what safety specs it had to be.

M is all they require for HPDE 1& 2 ... not sure about 3 & 4 ... pretty sure they require SA for TT and W2W ( probably closed face) I run HPDE 2 w/ them and only use my closed face when it rains.... no rain gutters on the CRX so wipers throw the water in to my face....bleh...