Lola - Ke55 4a-gze

[Des]

what is the max psi the chargers can handle before the teflon in them melts?.

if its high then I'm changeing my pulleys later

Edited August 29, 2006 by too quick

[ancullen]

There is a bit of confusion over this. A lot of people seem to think that it's the boost that kills the teflon seals, but I don't see how this can be the case. I think (and I'm not certain and only have a limited understanding of these things) that it's actually the heat generated by high rpm that kills the seals. Billzilla states in his 4A-GE mods guide that the speed of the tips of the rotors gets too high and melts the seals, so I'm basically just agreeing with him - the man is smart.

 

Bill Sherwood (Billzilla) reckons that a supercharger speed of anything above about 10,000rpm starts to kill the seals, so I'd stick with that figure. Of course, this figure is useless unless you know how fast the supercharger is spinning relative to the engine speed. On an early 4A-GZE which only produces 8psi, the supercharger spins at 1.2 times the engine speed. So when the engine's doing 7,500rpm (the standard maximum for a 4A-GZE), the supercharger is doing 9,000rpm. On a late model 4A-GZE, the supercharger spins at roughly 1.3 times engine speed, so when the engine's doing 7,500rpm, the supercharger's doing 9,750rpm.

 

Remember that both versions of the 4A-GZE actually make their maximum boost figures BEFORE the maximum supercharger rpm. The ABV will limit this boost though. Supposedly on the AE101 model (where max boost is 10psi), the supercharger gets to 10psi when the engine's at about 5,500 (so the SC is doing 7150rpm) and then the ABV limits it the rest of the way to the redline. I think it actually even drops it to 8 or 9psi at some point. Therefore, if you do the ABV mod to an AE101 4A-GZE, without worrying about changing pulleys, you should get a maximum boost of about 13.5psi at an engine speed of 7,500rpm. You should then be able to change the crank pulley to a Nevo/Cusco 175mm one, and still run the engine to 7,500rpm, you will get a supercharger speed of 10,937rpm. I don't know how long your seals would last like this, but you could in theory get a maximum boost of 15.9psi. I have heard of people claiming to get 16psi from their SC12's, so this is how they must have done it.

 

Of course, the other (less popular) way to get more rpm, and therefore more boost, from your SC12 would be to make the engine rev higher. This could be done with different cams to make the power band extend higher. Revving an AE101 4A-GZE to 8,800rpm would make the supercharger spin just as fast as swapping the crank pulley to a 175mm item. In fact, I have information that I've scoured the 'net for that gives an example of a guy in the U.S. with an AW11 with 4A-GZE who put 288-degree cams in his motor, along with some other minor mods, and got 188rwhp (140kW) at over 7,000rpm (he didn't say exactly how many rpm the engine was doing).

 

Considering there's a guy up here with a Sprinter with a 4A-GZE bottom end and 20v Silvertop head running a turbo and only making 120rwkw, it would seem far more cost effective to drop in some lumpier cams (not as high as 288-degree), switch to an aftermarket ECU, lift the redline, and enjoy the extra grunt.

[Des]

this question could be totally out of line but what about steel seals in the sc instead of teflon.they might leak a bit but i don't think they would melt as easy?

[ancullen]

Um, I wouldn't have a clue for starters. But I would think that it would a). be very expensive to get done as no one has bothered before, and b). wouldn't work, and c). why the f@$k would you bother? If you want to stay supercharged but want more grunt, go with an SC14, run it at it's maximum rpm (probably the same as the SC12), and you'll pump more air through than the SC12. Or go for another brand of supercharger. Personally, as stated in previous posts, I'll be going for a turbo of some kind, running about 18-20psi. It's not that much more boost than the supercharger, but the engine won't lose the power that it does trying to run the blower, so even if I stuck with the same boost, I'd pick up about 30-50hp at the engine.

[Killswitch]

What sort of setup you thinking of running Adam? In terms of respone, out right power etc?

[ancullen]

I want a very responsive, non-laggy motor, so that will restrict my turbo size somewhat. It is also going to have a 36mm air restrictor in front of the turbo as soon as I go into Improved Production, so I want to pick a turbo that will best suit that. Also, I do want to stroke the motor out with a 7A crank, block, and rods, so I'll pick up a little bit of torque there, and the 1762cc capacity will need to be considered when picking the turbo.

 

I won't be doing massive rpm due to the air restrictor and the 7A crank & rods, about 7,000-7,500 maximum, which is all it's doing now anyway. There are two Corollas with 3S-GTE's in Improved Production Racing in SA making 340hp. Obviously having a 2.0L engine versus a 1.8L engine will affect power output slightly, but I will be aiming to make 320-340hp at the engine, which I think is perfectly reasonable.

[Des]

when you do that^^^^^ can i come for a ride.its going to be a weapon. :D

[ancullen]

Sure, if you pay for some of the mods. :D

[Biggo]

lol, funny bugger

 

are they omy's wheels?

 

foxtail on here ran a bigport gze with sc 14 and 6500rpm limit till it blew. apparently it was making so much torque the exhaust cam slipped a tooth....something to think about.

[ancullen]

HOLY SHIT!!! That's insane. But are you sure that wasn't too much torque (tension) on the timing belt?

 

And yes, they are omy's old wheels. He's sold his Sprinter and is now looking at a Chaser.

[Killswitch]

HOLY SHIT!!! That's insane. But are you sure that wasn't too much torque (tension) on the timing belt?

 

And yes, they are omy's old wheels. He's sold his Sprinter and is now looking at a Chaser.

 

The chaser ken has imported? :D That thing is f@$ken sexy.

 

Ball bearing T28 variation on a 7AGTE ftw!

[ancullen]

Nah, Duy's gone south to check out a Chaser down there.

 

And I was thinking about a GT28RS. Duy has put me off a little though as he reckons it would come on full boost until about 4,500-5,000rpm. But then again, there shouldn't be too much time spent below those rpm when racing, so it shouldn't be too much of an issue.

[Killswitch]

Nah, Duy's gone south to check out a Chaser down there.

 

And I was thinking about a GT28RS. Duy has put me off a little though as he reckons it would come on full boost until about 4,500-5,000rpm. But then again, there shouldn't be too much time spent below those rpm when racing, so it shouldn't be too much of an issue.

 

That was also on a 1.6 wasn't it? Won't you eventually be running a 1.8 bottom end? I reckon talk to some of the CA18DET boys and see what setups they run, for good response and power.

[ancullen]

Yes, I plan on eventually going to the 1.8L bottom end. That's not too bad an idea on talking to CA18-types. I might do a bit of a search and see if I can find some dyno charts too.

[ancullen]

Here's some dyno results I just found:

 

This is from a Nissan Exa with a CA18DET with a T25:

 

This is the same car, now with a GT28RS and HKS cams:

 

Note the smooth power curve of the T25. It was supposedly a hot, humid day for this run, so power figures are probably a tad low. The same engine now with a GT28RS and the HKS cams goes from 100hp at 4,000rpm to 200hp at 5,000rpm. That's pretty scary.

 

I have just calculated what rpm my engine will be at when I change gears (eg. when I go from first at 7500rpm to second). When I get into second from the redline in first, I will have 4227rpm. From second to third I will go to 5133rpm. From third to fourth I will have 5419rpm, and fourth to fifth I will have 6457rpm. If my dyno chart were to be exactly like the second one pictured above (with the GT28RS), then when I go from first to second gear, then I will be right near the base of the steep power curve that follows 4,000rpm. From second to third and third to fourth, I'd be right near the top of the power curve. I had at first thought that this power curve was too steep, which it is in someways, but the main issue is that max power is at only 5,500rpm, leaving about 2,00rpm unused. I don't want a laggy turbo, but one that uses more of the rev band more effectively would seem better.