Turbo talk

[Kreator]

So yeah, i was talking to a friend of mine, and we kinda wondered in this direction and this is what we got stuck on:

Ok, i'm gonna make assumptions so bare with me...
Suppose 2 KA engines:

        One is stock:       The other is modded:
HP:    155 @ 5600             180 @ 6200
TQ:    160 @ 4400             140 @ 5000

Those are hypothetical numbers. Assume it's possible to mod KA that way.
Now imagine a very large turbo (say t76) which spins up to full boost at 5500rpm on the stock KA. So basicly the stock ka can't use any of the goodness provided by the turbo, since say to keep in the power band u gotta shift at 6000. Now the modded engine has a smoother curve and teh power band is a bit later in the rpms range.

The question now is, will the modded KA benefit from turbo more than the stock ka? Or because of the modifications and the torque drop it will now spin up turbo at later rpms thus eliminating the theoretical benefits? In our discussion we settled that hp and torque shouldn't matter since the only thing that spins the turbo is the exhaust gas (amount and velocity) which are directly derived from the rpms. Is that theory correct or there's something we are forgetting about?

[Mtt22]

well its simple, a t76 would blow up a completly stock KA, i beleive anyway

[Kreator]

Dude, it's an IMAGINARY world. Imagine that the engine is rebuilt and you are running 120 octane or something. But the hp/tq numbers are the same that i said in the beginning.

[270R]

Go read Import Tuner, That will answer all questions. It is the notorious ricer bible hehe. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wow.gif" border="0" valign="absmiddle" alt=':0'>

[Kreator]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (270R @ Sep. 20 2002,11:02)</td></tr><tr><td id="QUOTE">Go read Import Tuner, That will answer all questions. It is the notorious ricer bible hehe. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wow.gif" border="0" valign="absmiddle" alt=':0'></td></tr></table><span id='postcolor'>
OMG, can you just STFU and avoid replying to my posts?? It's not bad that u are a noob, it's bad that you don't want to learn. How about you just leave this msg board and go to clubsi or something?

[RedSuns]

A SERIOUS REPLY NOW!!!!



from my experiance with turbos......


in first gear it is harder to reach FULL boost faster but in ever gear after that you will hit full boost faster.....example.....in first gear i hit full boost at 4800rpms.....in 5th gear i hit full boost around 2900 to 3200rpms.....so the HUGE turbo KA will kick the crap out of the stock one..........

FLAME-RETARDANT SUIT ON!!!!!!!!!!!!!!!!!!!!!

[Jim96SC2]

I'd say it has more to do with flow. A stock KA with a small diameter downpipe and a restrictive intake is gonna spool slowly. On the other hand a KA with a nice tubular manifold, large free flowing exhaust, non-restrictive intake, ported and polished head will spool much quicker. So it would depend on what mods we have done to the engine to give it a HP boost.

[DSC]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (270R @ Sep. 20 2002,01:02)</td></tr><tr><td id="QUOTE">Go read Import Tuner, That will answer all questions. It is the notorious ricer bible hehe. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wow.gif" border="0" valign="absmiddle" alt=':0'></td></tr></table><span id='postcolor'>
Please try to just keep your mouth shut and learn something about cars before attempting to flame one of our older members when he is asking a very good question about turbos and powerbands. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/whatsthat.gif" border="0" valign="absmiddle" alt=':whatthe:'>

[Kreator]

No guys, you are missing the point. Suppose everything that might affect flow is the same. But say... the modified KA has shorter intake runners and say aftermarket cams. Suppose those things make it lose torque. So the question is, will the turbo spool up at the same rpm for both engines (thus more benefiting the modified engine since it's power band is later)? or will the turbo on the modified engine spool up at later rpms (eg slower spool up) cuz say it somehow is related to torque and thus the effects for both engines will be the same?

P.S. What i meant by stock in the first post was only reffering to the hp/tq numbers of the engine. Let's assume that the diameter of the exhaust, downpipe don't matter.Assume don't give us any hp/tq so life was easier.

[ca18guy]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Kreator @ Sep. 22 2002,05:26)</td></tr><tr><td id="QUOTE">No guys, you are missing the point. Suppose everything that might affect flow is the same. But say... the modified KA has shorter intake runners and say aftermarket cams. Suppose those things make it lose torque. So the question is, will the turbo spool up at the same rpm for both engines (thus more benefiting the modified engine since it's power band is later)? or will the turbo on the modified engine spool up at later rpms (eg slower spool up) cuz say it somehow is related to torque and thus the effects for both engines will be the same?

P.S. What i meant by stock in the first post was only reffering to the hp/tq numbers of the engine. Let's assume that the diameter of the exhaust, downpipe don't matter.Assume don't give us any hp/tq so life was easier.</td></tr></table><span id='postcolor'>
Everyone will probably have different answers cause they have different imaginary variables. &nbsp;Eveyone is going back to reality when they come up with there other variables (i know i am) &nbsp;What I think you wanna know is if the torque from the stock KA would spool up that KA faster then the lesser KA but the lesser KA is just as fast cause of the longer powerband? &nbsp;They will not spool up at the same time, KA#1 will spool up faster cause the torque will increase the velocity air through the turbo, but you will not be using the boost as long cause of the low shift point. &nbsp;KA#2 will take alil longer to get chugging but you have more roms to work with.

[Kreator]

Ok, i'll try to explain better. What i wonna know is whether the exhaust gas velocity is only affected by the rpms, or whether other stuff (tq, hp what not) also play a role. So basicly i don't care how fast it takes the engine to get to that rpm, what i care is will the turbo spool up at the same rpm on both engines.

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">They will not spool up at the same time, KA#1 will spool up faster cause the torque will increase the velocity air through the turbo, but you will not be using the boost as long cause of the low shift point</td></tr></table><span id='postcolor'>
So does that mean that the turbo on the first KA would actually spool up at lower RPM? Or do you just mean engine spool up (meaning KA#1 would get to that rpm faster)? But how does the torque affect the velocity of the exiting gas? Wouldn't it depend much more on the engine rpms??

[ca18guy]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Kreator @ Sep. 22 2002,06:21)</td></tr><tr><td id="QUOTE">So does that mean that the turbo on the first KA would actually spool up at lower RPM? Or do you just mean engine spool up (meaning KA#1 would get to that rpm faster)? But how does the torque affect the velocity of the exiting gas? Wouldn't it depend much more on the engine rpms??</td></tr></table><span id='postcolor'>
I believe the higher torque of the engine pushs more air per engine revolution at the lower rpm's making the turbo spool up faster. &nbsp;The second ka, with not as much torque, isn't pushing as much air at the lower rpms, so its not getting as much velocity for quick spool up.