Nigel

At the very least, this will help to minimize boost spikes (with an MBC at least). I have datalogs with the source on the manifold and on the turbo. With the source on the manifold, you can see boost pressure overshoot and then drop to the set pressure. With the source on the turbo, it hits the set pressure and stays there. This is with a Hallman MBC by the way. Not sure it's going to have much effect on surge though... Nigel '73 240ZT

Yeah, you're right. Like I said, I was really tired when I wrote that . But when you try to hold part throttle/low boost, you are backing off the throttle a bit. With a mismatched turbo, just lifting the throttle a bit can cause surge. A soft BOV spring will make the BOV far more responsive to smaller throttle changes like that. It doesn't get rid of the surge, which ideally you wouldn't have in the first place if the turbo is matched properly. However, a softly sprung BOV does make it far more livable. Believe me, I've tried it! My Z went from being undrivable under any boost except full throttle, to at least being somewhat enjoyable until I can replace the turbo. BTW Clifton... it was you who clued me in to the reality of part throttle/low boost surge in a post of mine last year. Thanks for your input! I couldn't figure out what was going on prior to that, and I was blaming it all on my BOV. But I've gone on to doing a lot of reading about surge and BOV's, and I've learned a lot. Nigel

As Clifton said, your turbo is probably not matched perfectly to the engine, so you're getting surge. I'm experiencing a similar problem (but mine is even worse!). You didn't notice it before because your old BOV did what it was supposed to do and vented the surge. The only problem from the sound of it is that it was leaking under boost. It doesn't surprise me that the lower gear didn't help. You're loading the engine more, but the flow is the same, so more surge (I hope that makes sense. I'm really tired, so in my state of mind, it makes sense to me right now ) I'll bet the new Tial is set too stiff, so it's not venting with low boost surge. The spring isn't really what keeps the valve closed under boost. The manifold pressure supplied by the vaccum line is what keeps it closed. It balances out the pressure against the valve in the intercooler plumbing that the BOV is attached to. The spring is really in there to keep the valve closed when you're not boosting. But if it's too stiff, it won't react to low boost surge. So, run a softer spring in the bov. You're not recirculating so it's not a big deal if the valve is open at idle. You will be drawing in some unfiltered air, but unless you're idling in a sand storm, so that shouldn't be a big deal either. I'm running a soft spring in my Greddy Type RS, with the tension backed almost completely off, and it holds 15lbs no problem. That helped tremendously. I still have some surge, but only a new turbo is going to solve that at this point. Nigel '73 240ZT

Wow! I didn't think I'd be a fan of the black rims, but that looks really evil! I love the flares too. I can't wait to see this when it's done. Nigel '73 240ZT

Here's another ebay vendor... http://cgi.ebay.ca/10-X-T-bolt-clamps-clamp-Turbo-Intercooler-Silicone_W0QQitemZ260206376616QQihZ016QQcategoryZ33742QQtcZphotoQQcmdZViewItem They're a little more expensive, but you can mix and match sizes... Nigel '73 240ZT

280ZX Marker Lights look pretty sharp IMO. They don't have the chrome retaining plate, so they look cleaner and more modern... Nigel '73 240ZT

SDS datalogging is very basic. You can only record AFR's for the RPM cells. It's handy in a pinch, but obviously, the more parameters you can log the better. I hooked up the EFI sensors to my TechEdge wideband 02 meter for logging. It has 3 user inputs + RPM and 3 EGT inputs (I wasn't able to get those to work though) Nigel '73 240ZT

2008 GTR... The face looks like the skin is being peeled off some hideous alien monster... and not in a cool way. It doesn't even look like a car any more. The dash looks like it came out of a pickup truck!

Being a Japanese car, the brake line fittings are metric, and the correct size is M10 with a 1mm pitch I believe. Also, there is a lot of confusion out there about the proportioning valve on Z's. Up to '72, the proportioning valve is at the rear of the car, mounted in line with the feed to the rear brakes. Starting at some point in '73 (maybe from the beginning of the model year), it was moved to the firewall (this distinction in 240Z's is not made in the Haynes manual). Unlike the earlier models, the valve is also tied to the front brake line, using pressure to the front right caliper to modulate pressure to the rear brakes. For the record, if you have a '73 or later Z with the proportioning valve on the firewall, you SHOULD NOT gut the proportioning valve, or you will tie the front and rear brake circuits together! If you want to replace the stock proportioning valve on a '73 or later Z with an adjustable valve, you need to splice the line going to the front, right caliper back together again once the stock valve is removed. Nigel '73 240ZT

Now that looks nice! Any interest in making more? I'd do it myself, but I doubt I'll ever have time... Nigel '73 240ZT

That looks like a Subaru Legacy Turbo Wagon to me, so that would be more like 160 hp and 180 lb/ft if it's stock. Still a far cry from 500 hp though...

I'm not sure you'd have the same issue with a dead-head setup, but I found that placing the regulator far away from the fuel rail caused significant fuel pressure problems. Here's the link to the post I wrote when I discovered this issue... http://forums.hybridz.org/showthread.php?t=105772 One other note... From my recent observations, I suspect that it's not hot fuel that's causing your AFR's to go out of wack on hot restarts, but rather the air temp. I have my IAT sensor in much the same place you do, and the air temps rise considerably when the car is shut off (as much as 60deg F). This leans out the AFR a lot on my SDS system, and I would imagine it does much the same for MS. Nigel '73 240ZT

I have an SDS EM3-6F, and I'm more or less following ScottieGNZ's recomendations for timing from way back when... So, I'm starting with a base timing of 20 deg at idle and ramping up to 38 deg by 2750 rpm. Scottie suggested pulling out a deg of timing for every pound of boost. I'm a little more aggressive at low boost and slightly more conservative at high boost. But like I said in my first post, at 12 pounds I'm at 25 deg total advance. I could bump it up more, but then which is worse, high EGT's or increased risk of detonation? Does no one else have an EGT gauge in their Z? Maybe these numbers are typical? I'm not doing anything out of the ordinary compared with the dozens of other L28 turbo's out there... Nigel

But, that's just it, I'm seeing 1600F with a stock cam...

My EGT's were in the 1400 to 1500 range running 9psi pre-intercooler. A couple of years ago, I put a heat blanket over my exhaust manifold, and I noticed my EGTs went up by 50 to 75F. My EGT's are 1400F cruising at 75mph at ~15:1 AFR and 38deg advance.

T3/T04B Turbo. I don't remember off hand all the specs other than I think it's a .63AR on the hot side and .7 something on the cold side. The engine is stock other than the exhaust ported on the head. I don't think there's anything too radical about my setup...

EDIT: TimZ responded before I had a chance to reply... Thanks guys... I've read through a lot of the posts already though, and there doesn't seem to be a lot of real world data on just what kind of numbers one can expect to see with an L28 turbo. I've seen TimZ's posts, but I think his engine is a pretty extreme case. How about for a garden variety L28 Turbo? Maybe 1600F is pretty typical for these too? I don't know, so lets see some numbers from personal examples...

I finally had a chance to wind out my Z through 3 and 4th gear up to 6K rpm with the new intercooler running 12psi, and I glanced down at my EGT gauge at one point to see the needle pointing at 1600F. That's the max the gauge goes to, so I don't know if it was higher than this. This is with 25 deg total timing and AFR's in the 11.5 to 12:1 range, so I was concerned to see the EGT's so high. I searched EGT and Turbo and came up with a few posts with others concerned about similarly high temps. But there doesn't seem to be a consensus on what's a safe or typical range for turbocharged L series motors. So how many people out there actually have an EGT gauge and what numbers are you seeing? Where do you have your probe placed? Is your exhaust manifold covered or wraped with any kind of insulation? What plugs are you running? What are your AFR's? What boost are you running? What is your total timing at that boost level? My specs for the record: EGT: 1600F (max gauge) Probe in manifold just before the turbo Exhaust manifold is covered by a heat blanket BKR7E plugs 11.5 to 12:1 AFR 12 psi 25deg advance Nigel '73 240ZT

How are the doors? Nigel '73 240ZT

I'm using an '86 to '91 RX-7 oil cooler. It's big (~ as wide as the rad), and it has a built in thermostat. Here's a link to one on ebay: http://cgi.ebay.ca/1986-91-Mazda-RX7-RX-7-Engine-Oil-Cooler-13B_W0QQitemZ250107151277QQihZ015QQcategoryZ46095QQrdZ1QQssPageNameZWD1VQQcmdZViewItem Nigel '73 240ZT

I've had good luck cutting braided hose by wrapping tightly with electrical tape before cutting it but the hose clamp sounds like an interesting idea. I've used both a fine tooth hacksaw and with a cutoff wheel. I found the cutoff wheel to work better. Nigel '73 240ZT

Ok, I found my post on zcar.com. It seems that the headlight connectors that I was looking at had "pass" and "drive" printed on them, and I was expecting "pass" to be the high beam and "drive" to be the low beam, which turned out not to be the case. So that may not be of much use to you. Are your headlight connectors clearly marked "Hi" and "Low"? Even so, maybe you should try a different combination. A friend of mine had his headlights wired in such a fashion that he had the same problem you did. The hi beams were dim compared to the low beams. It turned out that whomever had rewired the headlights previously, had reversed the low beam and common terminals. Consequently, when the high beams were switched on, the power was going through both the high beam and low beam fillaments in the bulb to reach common. I hope that makes sense... Nigel

If my memory serves me correctly, the markings on the headlight connector (hi, lo, com) don't actually correspond to the correct wiring. I think I may have posted about this either here on on zcar.com. I'll have a look and see if I can find my post... Nigel '73 240ZT

I hate to burst your bubble, but I don't think this swap is worth it if you're trying to combat fuel starvation in corners. I went through the trouble of putting a 280 tank in my 240, and with a high flow Walbro fuel pump, it was sucking air in hard left turns at not much below a half a tank. I ripped the 280Z tank out and put my 240 tank back in with a sump welded to the bottom. The best solution would be to run a surge tank which has been discussed extensively elsewhere on this forum. Believe me, I was extreemly frustrated after spending a lot of time and money to get the 280 tank in the car and still have starvation problems. Nigel '73 240ZT

I'm reviewing one of my data logs from the drag strip this past weekend, and I'm at 0 psi at 2700rpm and 12 psi by 3700 rpm at full throttle in third gear. That's with me taking it really easy in 1st and 2nd, and pausing before I floored it in third. At full throttle in 4th (with no pause shifting out of 3rd), at 4200 rpm I'm at 0psi and I'm at 12 by 4400 rpm. How do those numbers sound? I'll play with the BOV more this weekend. I think I need to back the adjustment screw right off. Like I said, I probably have it set too tight.