whats better? A 4th Gen Turbo Vtec or Turbo Si motor

 

neither. a swift kick in the *** is best.

imortal? psssha

doeboi returns!!!!

 

I always assumed that the H23 was better for forced induction....

 

I agree with that..h23 is better..I have heard problems with h22a's with boost, They don't respond well to it..

 

er... and why is that? The H22A4 maybe, because it's an open deck.

Get an H22A1, turbo it, and you'll be outrunning Si's.

 

Yeah those damn Si's are wimps.

 

Who said anything about wimps? I just said that a H22A1 was a great motor to turbo. The only reason why people like the Si is it has lower compression, and you can add cams to make the upper end resemble a VTEC profile. But cmon, the VTEC has a 30-40 hp head start. And if you do the fuel right, 10:1 compression can be a KILLER FI car.

 

Until I see some respectable turbo H22A dyno's I agree that the H23A is better.

 

Yeah.

 

Purelude just dynoed 250 @ 7 psi with an H22a4 and a properly sized turbo. He posted it on the FI forum.

 

Does anyone have any real, first-hand evidence that the H23 is better to Turbocharge? What goes wrong, etc. I currently have an H23 in my lude and am eventually going to put a JDM H22. Should I just keep mine and Turbo it?

 

You'd get more power out of a turbo kit on your H23a, than if you bought an H22a and swapped it into your prelude. That should answer your question unless you want to go JDM all the way.

 

But a JDM Turbo H22 would be better or worse then a Turbo H23?

 

But why does a H23 produce more power than a H22? There have to be actual technical reasons (not just "because")...

 

i dont' think its a matter of which produces more power. everyone is just saying that an SI is easier to turbo, because it doesn't have the VTEC system to deal with. as far as power gains go, they should be similar. that would still leave the Si behind, but then again, if you can't get the VTEC to work properly then it may just screw the whole system up.

 

why does VTEC pose an obstacle to turbo tuning?

 

Does anyone in here actually know what they are talking? All I'm hearing is a bunch of speculation. Does anyone have any first hand experiance with turboing Preludes (vtec AND si). Any real, edjucated advice would be great thanks.

 

Errr... I second that motion...

 

I know a couple things.

 

Edjucated??? or EDUCATED, Experiance???? or EXPERIENCE

 

4th gen vtec 93-94 is closed deck.. the block is strong but the compression is high so you can't boost that much
si motor has a lower compression to begin with and you can boost more than a vtec assuming the internals are stock vs stock..
i had a dyno of a 5th gen @7lbs registering 253whp
bottom line.. both are good, vtec 4th gen is hard to find and si is more abundant has a lower price tag *hint*

 

Ok, but what I am looking for is what the problem is with turboing VTECs. Is the problem the fact that you can't boost their power up as mucgh as you can the Si? Or is there REALLY something WRONG with Turboing a VTEC. Also, I know a Turbo Si would be faster than a VTEC, but would it be faster than a Turbo VTEC?

 

Well for one, if you turbo an h22a your more than likely going to have to disengage VTEC, and you would want to get lower compression pistions ... and to answer your questions ... if you have an si with stock internals and a turbo and the same with the vtec model ... then yes, the si would be faster and produce more hp because you can boost higher because of the lower compression. It will cost you a lot less money to turbo your current motor than to buy an h22a and turbo it ... just add it up...

h22a - 2500+
turbo kit 3000
lower compression pistions - 1000
total = 6500

now drop 6500 into your si ... it will tear that turbo h22a a new ******* ... and a lot of other cars for that matter imo, vtec cars are better for n/a ... just my .02 ...


-Mike

 

no offense yellow lude, but why would u have to disengage the vtec?

also, if u are running low boost say 6 to 8 psi maybe, then having a 10 to 1 cr is better than a 9to 1 Cr, Cr being high just means more tuning and less boost, so depends on the setup that u want!

 

You don't NEED to disengage VTEC for turbo applications. It'll help with tuning, but not really necessary. And why would you want to be on only the SMALL cams? The PROBLEM with turbo and VTEC is that when the bigger cams come online, they tend to throw the fuel/ignition timing off when in boosted form.

When the VTEC system kicks in, the immediate extra airflow from the higher lift/longer duration cams can also disturb boost pressure. So we're left to tune around the VTEC x-over point. Everything else should be fine since it's pretty much linear and progressive.

If you don't want to deal with all of this mess, get an Si with HUGE turbo cams. You'll always be on the BIG cam, without having to tune for the x-over. But then again, you won't have VTEC or the gas mileage you can SOMEWHAT get with the VTEC system and turbo. But if you're out for all out power, with no regards to gas mileage...go with the Si, port the heads, and get some turbo-specific cams for your turbo setup.