Zmanco

Tony, I understand that these are two different issues and in my case, I am only concerned with modulating boost when I'm well past the boost threshold. I have a ZX 5 speed with 4.11 diff so as long as I'm not lazy with shifting, it's easy to find a gear where there's boost right NOW. I'll take a walk around the pick n pull some time and see what can find for throttle cams. It's been a while since I read Derek's thread on his linkage so I'll re-read that as well. I've been thinking of adding a rear spoiler, but not as big as the wing you describe. Hence I don't think it would add enough downforce to really solve my problem, although I expect it could help.

You have a PM.

I suppose the better solution would be an electric boost control actuator that could be controlled by Megasquirt. MS2/Extra has a table to limit the max boost as determined by engine rpm and throttle position. But right now, the only way it works is by bleeding off pressure to the mechanical actuator which allows it be increased above 8 psi, not decreased which is what I need in this case. Anyone with metal working skills think they could make an eccentric cam for the 240sx TB for use with a throttle cable? It might not be the perfect solution, but it seems like it would help.

The heater valve is up there as well and could be the source of the leak - at least it is on my 73 - you didn't say what year.

Do you want to trust your safety with belts that are more than 30 years old? While I've not seen any hard data that proves this, the consensus appears to be that over time the strength of the belt material deteriorates. If you have to buy belts anyway, why not buy new ones? I went with lap/shoulder belts from Wesco Performance http://www.wescoperformance.com/seat-belts-racing.html but I'm sure there are other sources as well.

Here's a thread I started a while ago with a similar topic: http://forums.hybridz.org/index.php?/topic/68330-thoughts-on-this-aluminum-radiator/page__hl__radiator From JohnC's response in post 17:

Right now I'm just running with a mechanical wastegate actuator which is preset to 8-9 psi. I do have a solenoid in the circuit controlled by megasquirt for boost control, but it can only increase the boost level, not reduce it. As much fun as more power is in a straight line, it only makes things worse on the track.

Thanks Tony, I had been looking around for a while for an eccentric cam but haven't found one yet. And I wouldn't mind getting rid of the stock linkage (which is a bit kludgey when used in a 240z) anyway. Any chance you can remember which Mazda? Indeed, the throttle response once above 3k is nearly instantaneous. The challenge is modulating it so that I don't get full boost in the middle of the corner when already at the limit of traction I expected that, but since the wastegate gets its signal directly from the intake manifold, I would expect that the turbo would just run to a slightly higher level of boost to compensate for the drop across the TB. I do like your idea of an eccentric cam better though. Anyone else know of any that would bolt up to the 240sx TB?

I think Moby is on the right track. The LC-1 has two outputs, each of which is programmable for the range of output voltage. I can't tell from this thread if you've checked them, but it sure sounds like the LC-1 output is not matched to what MS is expecting. BTW, you should also reload the AFR table in case it became corrupted - Tools\Calibrate AFR Table in TunerStudio (not sure what it's called in MegaTune).

I've read quite a few threads about the downsides of using too large of a throttle body. I currently run a 60mm 240SX TB with a stock intake manifold on my L28 turbo motor. Turbo is a T3/4OE, head is P90 shaved with unshrouded valves, currently running with a Schneider stage II turbo cam, good sized intercooler etc. I'm staying with 8-9 lbs boost for now as I learn to drive with the extra power. Driving is on the street and road courses - no drag racing. As some have predicted, the throttle is difficult to modulate when on boost between 3500 and 7k rpm. For example, I can generate full boost above 3500 rpm with around only 50% throttle. The 2nd half of the pedal movement makes very little difference. And it's hard to modulate that much power in such a small range of throttle opening when in high-G corner. I know my setup is pretty common here on hybridz so was wondering if anyone has tried both the 60mm TB as well as the stock one and can let me know how they differ in terms of throttle control? I'm considering putting the stock back on to help with driveability and wondering how much better it will be? Also wondering if dropping down to 50mm for the TB will make that much of a difference on peak power given I'm running with 2.25" intercooler piping anyway. Thoughts?

That's where I mounted mine when I ran NA with a header. The farther from the engine the longer the delay (obviously) but for a carb'd engine I can't think why that would matter. For fuel injection with Megasquirt, I found that only mattered when using the datalog analysis tool called Megalogviewer. The new TunerStudio also requires you to enter delays in order to use its autotune feature. If you enter accurate values both tools can be made to work well.

A few things: - There are a variety of things that contribute to exhaust in the cabin including worn seals, poor hatch alignment, etc. If you haven't solved those, then I doubt this will help much. - Read the wind tunnel tests specifically looking at the tests with the rear spoiler. I think you'll find that the BRE does make a difference in terms of reducing lift, but it's small because the spoiler is small. A bigger spoiler is really required to make a significant difference. - The one you show is even smaller than the BRE so I'd expect it to have little impact on the airflow, and hence on fumes. - I've seen a small number of people post their experiences after adding a rear spoiler and I'd say the general consensus is that it doesn't make much difference.

Glad you got it up and running. I'm not home this week so can't look under the car to be sure, but I searched for a fuel pump for an '80 RX-7 at O'Reilly and got this: http://www.oreillyauto.com/site/c/detail/ATN0/E8016S.oap?year=1980&make=Mazda&model=RX-7&vi=1192238&keyword=fuel+pump&pt=C0401&ppt=C0025 I'm pretty sure that's what I have on my car now feeding the surge tank. It's quiet, been bullet proof reliable for a few years now, and can feed enough fuel to keep the engine happy, even now that I have the turbo. I ran this pump without a regulator feeding SUs as well as triple webers and never had a pressure problem. I'm sure you're not looking forward to changing the pump again, but...

The NGK BPR7ES has a traditional ground electrode. I run them as well but limit advance to around 10 degrees at boost above ~10 psi just to be safe.

The Holley regulator came as part of a package deal with a Holley Blue fuel pump IIRC. I just looked at the spec on the link you posted and it's only rated to go as low as 4 psi. The issue as I remember it is that the regulator adjusts by loosening a screw that applies pressure to a spring that in turn applies pressure to the regulator mechanism. The lower the spring pressure the lower the fuel pressure. The problem was that the screw was about to fall out at its lowest pressure setting and I suspect the poor machining of the parts resulting in stiction and other inconsistent movements. In any event, as I said earlier, I suspect that's why there are $300 regulators. Of course you can try it with the mr. gasket pump and see, but I'm doubtful it will work well. I really think you need to find a low pressure high volume pump like the Facet or RX7. It's an interesting idea to drop the voltage to the mr. gasket pump, but I doubt you have a potentiometer that can handle the current required. You could try some wirewound resistors, but unless you already have them, I wonder if you wouldn't be better off just getting another pump. BTW, you might try looking for a low cost generic that's spec'd for the early RX7. Perhaps something else will show up? Good luck!

Thanks sticky280zx, I can understand if it's just for looks, even though it's not my personal choice. For a while I was wondering if this was some new-found secret to enhanced tire performance ...

I can relate to your frustration - been there (and likely will be again too). The issue I had was that the output pressure wasn't consistent from minute to minute. I figured there was a reason why there are $300 adjustable regulators. Or maybe I just had a bad unit? Perhaps someone else can chime in with another suggestion.

You guys are making me miss the sound of my triple webers! You've got the best of the sound, but without the hassle (and cost!) of tuning. Sweet.

The Facet pump I had was one of these two but I don't remember which one: http://www.pegasusautoracing.com/productdetails.asp?RecID=82 http://www.pegasusautoracing.com/productdetails.asp?RecID=83

The floats are being overwhelmed by the pressure above 3 psi which is why they are spitting out the vents. They need to be open to atmospheric pressure so don't connect them to the vent line. They were plumbed to the air filter by the factory in order to capture the vapors and have the engine burn them. I went through the same issue of trying to regulate to 3 psi when I was running SUs. The problem I found with this regulator is that it really wants a larger input pressure. It did not maintain a consistent pressure with a relatively low input pressure. I hate to say it, but I think you should be looking for a 2-3 psi electric fuel pump. I'm afraid I don't have any part numbers to suggest, although I know there are many who like the early RX7 carb'd pumps which don't need any regulator and are supposed to be very quiet too (in case that matters to you). I know that Facet (or is it Faucet?) makes a cheap pump with 2-3 psi output, but it's pretty noisy. That's what I ran until I switched to Megasquirt. It was shaped like a cube I think, about 2" x 2" x 2"? I'll bet you could find one of these at Autozone or O'Reilly's for about $25 as generic replacement.

Since no one else is asking, I'll do it. What is the point of going with such a wide wheel and then using such relatively skinny rubber? If you're only going with 215 or 225 rubber, why not just use a 7" rim? What am I missing?

You know how the announcers usually say something like "The safety car has been deployed and is picking up the leader ..."? This brings new meaning to the phrase "picking up": http://cdn.static.viddler.com/flash/publisher.swf?ref=http://www.google.com/reader/view/&key=4720ead5

BTW, instead of tuning with Megatune's Autotune feature, run the latest version of TunerStudio. It has a new feature called VE Analyze which is far superior to autotune.

Why not look for an MSII v3 board? The wiring is essentially the same and you can run MS2/Extra firmware which has many more features than MSnS, some of which are really nice to have on a turbo engine.

I'm pretty sure that since the factory coating is unaffected by gasoline that it won't be harmed by lacquer thinner either. Unfortunately I am only "pretty sure".