Lola - Ke55 4a-gze

[love ke70]

i was going to say the same thing. the sc12 just can't keep up.

by 9000 the drag on the motor is going to be huge from the supercharger and it will infact be restricting air flow.

but that is simply my belief, ive never built one before.

go ahead, and tell us how it goes.

you wont have lost anything, you can then just bolt a turbo on :)

[ancullen]

Solution: 18% underdrive crank pulley (123mm diameter) and 90mm supercharger pulley (use a Falcon air con pulley). Should solve the problem nicely.

[ancullen]

Here's some GT-Four footage to keep you all entertained:

 

http://www.youtube.com/watch?v=AsXVHzWQg5U

 

This was taken today at a motorkhana. I only did three courses in the GT-Four as it shredded the front left tyre and I couldn't use the spare as the wheelnuts don't fit it. :D

Edited October 14, 2007 by ancullen

[ancullen]

Took the GT-Four out on the track again on Sunday the 28th of October. Got a best of 1:31.63. That was with very worn semi-slicks on the front, very worn street tyres on the rear, and EXTREMELY worn brake pads. Also spun out in this car for the first time (through turn 11). Did a full 360-degree turn, which shows just how much quicker I was moving when I spun than in previous cars. My previous best is a 270-degree turn. :P

 

Over the Christmas break I plan on getting some work done to get Lola back on the track. The things I need to do are as follows:

Source and fit replacement ignition coil

Check if tailshaft needs replacement/fixing

Fit new racing bucket seat :wink:

Construct cage or support bars for racing harness

Fit harness

Install Pajero master cylinder & reservoir

 

Things I would LIKE to get done:

Fit Commodore brake pads or upgrade to RX7 front calipers

Lower the rear end

Fit new, better shocks all around

 

I've also been doing further research for my engine plans. In light of a discussion from a month or so ago on these forums, I've come to realise that I will not be able to build as much power as I want without changing pulleys or the supercharger itself.

 

The way I figure it, the SC12 can provide 1200cc of air per revolution. The 4A motor is 1587cc, so for every revolution of the engine, it must take in about 1587cc of air (if the engine is drawing it in naturally). With the standard pulleys, the SC12 is spun at 1.25 times engine speed. Therefore by the time the engine reaches it's maximum 7,500rpm, the supercharger is providing 11,250L of air per minute, and the 4A is sucking in 11,902.5L of air per minute. Therefore there is a shortfall of 652.5L of air per minute.

 

If we then work out the air supplied with a 175mm crank pulley, we now find that the SC12 is being spun at almost 1.46 times engine speed. Therefore at 7,500rpm engine speed, the SC12 is spinning at 10,937.5rpm, and is therefore providing 13,125L of air per minute. This means the SC12 is providing 1,222.5L of air more than what the 4A is attempting to suck down. I believe that this is why bigger crank pulleys give the 4A-GZE significantly more power, and they should in theory also improve the top end as well as the rest of the rev range.

 

However, I have been tempted by the prospect of the SC14 supercharger, especially after discovering that it is actually relatively easy to install, contrary to what I'd previously heard.

 

Using standard pulleys, the SC14 would be spun at 1.25 times engine speed. The SC14 has a volume of 1420cc vs. 1200cc of the SC12. Therefore when the engine is spinning at 7,500rpm, an SC14 on standard pulleys should supply up to 13,312.5L of air per minute. That means it's providing 1,410L more air than the 4A is attempting to induce. What's more, that's better than the air provided by an SC12 with a 175mm crank pulley! And the supercharger doesn't need to be spun ridiculously hard and out of it's efficiency range, which creates more heat.

 

So I'm extremely interested in doing an SC14 conversion now. However, I still like the idea of using lightweight pulleys. Especially with the added drag of the heavier SC14 internals (it's bigger, so they've got to be proportionally heavier). I also like the idea of running the supercharger constantly - it's for racing, so it only gets used for short runs anyway. Plus I've discovered that by running it constantly, the supercharger internals are apparently kept cooler by the air rushing through them.

 

With this in mind, I've decided that I like the idea of using an SC14 with an undersize supercharger pulley without any clutch mechanism. NST make one in 102mm diameter. With this I would use NST's 160mm crank pulley. This is the smallest oversize pulley they make. My reasoning for the pulley change is that both pulleys are made from 6061 aluminium, and I figure this must be lighter than the standard pulleys. With a 160mm crank pulley and 102mm supercharger pulley, the supercharger will be spun at almost 1.57 times engine speed. Therefore at 7,500rpm at the engine, the SC14 would be spun at up to 11,764.7rpm, which should mean it's not making the air too hot (I know of SC12's being spun at up to 13,235rpm), and it should provide up to 16,705.9L of air. That means it will be providing an excess of 5,455.9L of air to what the 4A is sucking down, meaning higher boost.

 

Of course, this is all just more theory, but I intend to test it when I finally start building the engine. I will still be getting a lot of headwork done, and my current cams of choice are 288-degree, 11.65mm lift items. Hoping for 300hp at the engine, or 160+rwkw. Again, the only way to find out is build it and find out. :n:

[Pure-SX]

Adam lives in a unit, not house :P.

 

Please just hurry up and get it done as to not change your mind anymore. I want to take it for a drive(passenger at least :wink:)

[Hiro Protagonist]

I've seen a couple of supercharged 20v, mostly in Clubmans though, and they've all used Rotrex superchargers (ie centrifugal, not Rootes like the SC12/14)

[ancullen]

What's a 20v engine got to do with it? I don't want to use a 20v head, just the throttles. I've got an AE101 4A-GZE...

[Jason]

mmmmm quads... they still have a larger surface area than my 2.75inch throttles !

 

also on the note of the volume of the SC12 that is interesting that it seems to choke the flow? may make up in compression though? Though IIRC the cylinder carnt aculty suck in its full volume of air in the intake stroke.

[ancullen]

The cylinder may not be able to suck in it's full volume of air, but it's a good, basic way of comparing the values. With the SC14, the supercharger should be creating significantly more boost and forcing more air into the cylinders.

 

Although the bigport intake manifold would be significantly cheaper to do, the temptation to do quads is HUGE. Plus it'll make my 4A-GZE even more different from everyone elses.

 

Then once it's all built I'll just have to try and resist the temptation to build it into a 7A-GZE or even get a 1900cc kit from Speed Racer.

[Jason]

:P

 

you have to get some values for how much thee quads stick out, becese when i though about it the room for clearance is very very small, even with the bigport its very very small. some other people with similar setups have even less clearance than me!

 

Just because you have to off set the charger so much. I overcame it a little by spacing out the bracket from the block.

Edited November 2, 2007 by Jason

[ancullen]

But if we construct our own inlet manifold to put the quads on the bigport head we could angle the throttle bodies upward significantly to easily clear the SC14. :P

[love ke70]

wouldnt it be easier to just make a different bracket for the supercharger?

 

and with forced induction the cylinder should be getting its full fill, then plus some.

whereas n/a it only fills to a certain extent, different figures seem to be bandied around all the time, but thats the difference i can gander.

 

and with the 1900cc kit, what is the bore and stroke? and how much do you have to clearance the block?

the HKS 2400cc kit for the 1g is actually only 2250 or so, and has a clearance in the block about 70mm long for the extra 4mm stroke

[Jason]

^^ about the air filling I'm not 100% sure, been awile since ive looked at the phy behind it.

 

But as for the bracket, its fine for the bottom mount, because you carnt really put it anywhere else (hits engine mount if to low or to far back and carnt bring any higher because well.... your trying to move it away from the intake lol)

[love ke70]

move it away and never looked at a 4a in terms of fitting an sc14 but surely a big chunky braced to the hills mount can be fabbed to move it away and down or whatever is needed, it only spins one direction so the forces shouldnt be too bad, surely?

[Jason]

forces no, but you carn move it down, becuse it hits the engine mounts, i was going to move it down and fowared and run it off the anc. pully, but i CBFed