GT28 vs K24 pros and cons
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I don't think the price difference is staggering. There are vendors selling 18G "kits" for $5500-$6000. You can buy TiAL's GT28's (turbos only) from Titan or EPL for $3500-$3800? How much are 18G's only? $3000? $3500? I think the new technology is worth the extra couple hundy.
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I think the jury is still out on the new Alpha series GT28's. On paper they look very promising. The K24/18G is proven and sets a fairly high bar for a simple bolt on package. They spool very quickly, have a fairly strong top end and are a great all around turbo choice. What we need now is for some Alpha GT28's to run the 1/4 mile a few times and show us some ET's and trap speeds. IMO, if they can run high 10's with AWD, at full weight, on street tires, at about 1.3 bar, with an average driver like myself, then that would be compelling. Additionally, if they can consistently trap upwards of 133 MPH in said runs (AWD, street tires, full weight), that would be an additional confirmation of their performance. I have not seen any 1/4 mile times for the Alpha 28's yet, but would be very interested to see what these can do...
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Great first run!
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Cossey,
Thanks for the info - that's interesting data, but I think we need a few more runs with drivers pushing the car through all the gears to know the true potential. Did you make any other passes and if so, what were the trap speeds like?
Out of curiosity, why didn't you get on it in 2nd? I can sort of understand 1st due to transmission wear and wheel spin concerns, but 2nd is normally not a problem with AWD.
If it gives you any confidence, I have launched my car from moderately hard to very hard in 1st every time (about 40 passes), but I can understand your reluctance to do it. If you stay away from drag radials, these cars spin like crazy in 1st, relieving a lot of the power from the transmission. In fact, I have to go a little easy in 1st to even think of hooking up. A high RPM launch, unless you really feather and burn the clutch, will result in massive wheelspin and a slower ET.
Thanks for the info - that's interesting data, but I think we need a few more runs with drivers pushing the car through all the gears to know the true potential. Did you make any other passes and if so, what were the trap speeds like?
Out of curiosity, why didn't you get on it in 2nd? I can sort of understand 1st due to transmission wear and wheel spin concerns, but 2nd is normally not a problem with AWD.
If it gives you any confidence, I have launched my car from moderately hard to very hard in 1st every time (about 40 passes), but I can understand your reluctance to do it. If you stay away from drag radials, these cars spin like crazy in 1st, relieving a lot of the power from the transmission. In fact, I have to go a little easy in 1st to even think of hooking up. A high RPM launch, unless you really feather and burn the clutch, will result in massive wheelspin and a slower ET.
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The alpha turbo spools quicker and makes similar if not better top end power compared to 18g cars. It will be more fun to drive around town and be just as fast on the freeway. Tony has pretty much said as much. Isn't that pretty obvious?
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This is my theory about quick spool: Quick spool usually goes hand in hand with less top end. In the first gear you rev out, the quick spool will help, but once up and running, every time you shift, you are past the "quick spool" portion of the RPM band and you need the top end of your power band to perform. The "quick spool" is not even being utilized after the first redline shift. Now, if the A28 has a "better" top end, as well, then it should be game over, but if the 24/18G is stronger up top, then it's not so clear cut, as the turbo with the better top end will pull harder in all subsequent gears. Ultra quick spool with a big top end is the ultimate turbo, but up until now, it has sort of been one or the other. If the A28's have both, they they will emerge as the champion. If, however, they lack the top end vs. the 24/18G - it could be a real battle for the A28. Time is going to show how they fare against each other and a lot of us are very interested to see how it goes.
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True, but that theory doesn't help in-gear passing and throttle response in general. Having gone from K24s to 2860s (I'm still not sure wether my car has the alpha series or not), I can tell you that the car is much faster in all street situations. It seems any transition from cruise (barely open throttle) to WOT results in signficantly faster response and power. Even in first gear where the K24s never had time to spool. It feels like you are driving turbocharged V8. With the K24s it felt like you were driving 6 cylinder with big turbos.
Those diverter valves are working overtime these days trying to blow off excess boost when you let off the throttle
Those diverter valves are working overtime these days trying to blow off excess boost when you let off the throttle
This is my theory about quick spool: Quick spool usually goes hand in hand with less top end. In the first gear you rev out, the quick spool will help, but once up and running, every time you shift, you are past the "quick spool" portion of the RPM band and you need the top end of your power band to perform. The "quick spool" is not even being utilized after the first redline shift. Now, if the A28 has a "better" top end, as well, then it should be game over, but if the 24/18G is stronger up top, then it's not so clear cut, as the turbo with the better top end will pull harder in all subsequent gears. Ultra quick spool with a big top end is the ultimate turbo, but up until now, it has sort of been one or the other. If the A28's have both, they they will emerge as the champion. If, however, they lack the top end vs. the 24/18G - it could be a real battle for the A28. Time is going to show how they fare against each other and a lot of us are very interested to see how it goes.
Last edited by Turbo Fanatic; Jun 5, 2009 at 01:31 AM.
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This is a very interesting thread. I'm looking forward to more data, especially in the form of 1/4 mile and 60-130 times for the Tial Alpha series GT28's. Sure would be nice to see a , heads up run of 24/18 against a GT28 Alpha series car. with equal or atleast similar setups turbo's aside.
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This is a very interesting thread. I'm looking forward to more data, especially in the form of 1/4 mile and 60-130 times for the Tial Alpha series GT28's. Sure would be nice to see a , heads up run of 24/18 against a GT28 Alpha series car. with equal or atleast similar setups turbo's aside.
I also look forward to the results.
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I think a race between a K24/18G car and a twin turbo z06 would be interesting too
. But I guess that's not what this thread is about...
