Go Back   HondaSwap Forums > Honda Tech :: General Honda Performance > Forced Induction

difference between turbo sizes

Welcome, Guest! Please Register or Login:
  

Members have access to more features, better search, and see fewer ads! It's free, what are you waiting for?

Reply
 
LinkBack Thread Tools
Old 11-12-2002, 03:47 PM   #1
Senior Member
 
Join Date: Sep 2002
Location: Utah
Posts: 278
iTrader: 0 / 0%
Rep Power: 17 SnailOnARampage is off the scale
Send a message via MSN to SnailOnARampage
Default

Okay, I am a little disturbed by the fact that nobody has every really explained this in full to anyone. I hear newbies say... If i run xx pounds of boost on a t3, how many hp will I get? and then they get responses like.... psi doesnt mean shit...it is how large the turbo is. Yes, that is true...but only under certain circumstances.

The rule is this: 8psi is 8psi coming from any turbo (big or small), as long as there is no pressure drop at the high end due to your engine being able to suck in more air than the turbo can blow.

If you had a guage in your h22a prelude that showed how many psi the turbo system was running at, and you were running 7 psi on a t3 ( or some small turbo) the guage/rpm would look something like this:

remember I am just using these as a visual...these are not actual numbers from a dyno..they are just out of my brain.

1000 rpms: 0 psi
2000 rpms: 0 psi
2500 rpms: 4 psi (+ 25 percent more tq theoretically)
3000 rpms: 7 psi (+47% more tq..theoretically)
3500 rpms: 7 psi (+47% more tq..theoretically)
4000 rpms: 6 psi (+40 % more tq..theoretically)
4500 rpms: 5.5 psi (+ 37% more tq..theoretically)
5000 rpms: 4.5 psi (+30% more tq..theoretically)
5500 rpms: 3 psi (+20 % more tq)
6000 rpms: 3 psi ( +20 percent more tq)
6500 rpms: 2 psi (+13% more power)
7000 rpms: 2 psi (+13% more power)

so...if the power peak for the h22a engine was at 7000 rpm, you would have 170 ft/lbs instead of 150 ft/lbs...but your average torque from 2500 to 6000 rpms would be something like 35 percent higher.

that same small turbo on a d15b7 at 7 psi might look like this:

2000 rpms - 0 psi
3000 rpms - 0 psi
3500 rpms - 3psi
4000 rpms - 6 psi
4500 rpms - 7 psi
5000 rpms - 7 psi
5500 rpms - 7 psi (47 percent increase in torque from 4500 rpms to red line)
6000 rpms - 7 psi

what if you put a big ass turbo on a d15b7?

2000 rpms - 0 psi
3000 rpms - 0 psi
4000 rpms - 0 psi
4500 rpms - 0 psi
5000 rpms - 3 psi 20 percent more tq
5500 rpms - 5 psi 35 percent more tq
6000 rpms - 7 psi 47 percent increase in tq

notice how the average torque gain is a lot lower than the smaller turbo, and the peak torque gain is the same?


that same large turbo on a h22a might look like this:


2000 rpms 0 psi
2500 rpms 0 psi
3000 rpms 2 psi
3500 rpms 5 psi
4000 rpms 7 psi
4500 rpms 7 psi
5000 rpms 7 psi 47 percent increase in tq
5500 rpms 7 psi
6000 rpms 6.5 psi 44 percent increase in tq
6500 rpms 6 psi 40 percent increase in tq


Horsepower = torque x rpm/5252

If the h22a had 150 ft/lbs of torque w/o boost, with 7 lbs, it would have close to 220 ft/lbs of tq.

the h22a @ 7k rpms w/o boost would have 199 hp/ 150 ft/lbs
the h22a @ 7k rpms w/big turbo would have 293 hp/ 220 ft/lbs
the h22a @ 7k rpms w/small turbo would have 226 hp/ 170 ft/lbs

the d15b7 @ 6k rpms w/o boost has 102 hp / 98 ft/lbs
the d15b7 @ 6k rpms w/big turbo would have 150 hp and 140 ft/lbs
the d15b7 @ 6k rpms w/small turbo would have 150 hp/ 140 ft/lbs, but it would have one hell of a lot more power throughout the whole power band...making it a much better daily drivable car

A b16/b18 would be somewhere inbetween the d15/h22a

this is my 2 cents on turbos...hope it helps someone
__________________
The object of war is not to die for your country, but to make the other bastard die for his.
SnailOnARampage is offline   Reply With Quote
Old 11-12-2002, 04:01 PM   #2
Senior Member
 
Join Date: Sep 2002
Location: Utah
Posts: 278
iTrader: 0 / 0%
Rep Power: 17 SnailOnARampage is off the scale
Send a message via MSN to SnailOnARampage
Default

If you had 7 psi at the throttle body coming from a t3, it would have the exact same increase in torque/power as 7 psi at the throttle body coming from the biggest ass turbo you can find. the only difference is when you step on the gas, there might be a drop in pressure from the small turbo because the engine can suck in more cf/m than the lil turbo can produce. the big turbo, however, would continue to stay at 7 psi.
__________________
The object of war is not to die for your country, but to make the other bastard die for his.
SnailOnARampage is offline   Reply With Quote
Old 11-12-2002, 04:05 PM   #3
Senior Member
 
Join Date: Sep 2002
Location: Utah
Posts: 278
iTrader: 0 / 0%
Rep Power: 17 SnailOnARampage is off the scale
Send a message via MSN to SnailOnARampage
Default

make sure you get the right size of turbo for the application.

If you are going for more power for daily driving, go with a smaller turbo.

If you are going for drag racing, get a larger turbo, but dont get one larger than it needs to be, because you will actually lose peak horsepower.

This is because it does actually take energy to push the turbo, and if you are pushing it harder than it needs to be, you are just wasting horsepower to push air through the blow off valve
__________________
The object of war is not to die for your country, but to make the other bastard die for his.
SnailOnARampage is offline   Reply With Quote
Old 11-12-2002, 04:53 PM   #4
Admin with a big stick
 
Calesta's Avatar
 
Join Date: Sep 2002
Location: Dallas / Fort Worth, TX
Age: 32
Posts: 24,525
iTrader: 0 / 0%
Ride:  2003 S2000
Rep Power: 291 Calesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant future
Send a message via AIM to Calesta
Default

Hmm. I've got a clearer explanation using some real numbers.. but I have to write it up real quick. I was going to link to Brian's article, but it's somewhat confusing still.... I'll post here as soon as I rewrite the article.
__________________
DO NOT PM me with tech questions! Use the forums!
Intercrew Auto Salon - (972) 485-8688
Calesta is offline   Reply With Quote
Old 11-12-2002, 04:53 PM   #5
Admin with a big stick
 
Calesta's Avatar
 
Join Date: Sep 2002
Location: Dallas / Fort Worth, TX
Age: 32
Posts: 24,525
iTrader: 0 / 0%
Ride:  2003 S2000
Rep Power: 291 Calesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant futureCalesta has a brilliant future
Send a message via AIM to Calesta
Default

Oh yeah- here's Brian's article:

http://www.hondaswap.com/turbo/viewer.php?id=8
__________________
DO NOT PM me with tech questions! Use the forums!
Intercrew Auto Salon - (972) 485-8688
Calesta is offline   Reply With Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
b16a turbo or ls turbo allmotorbeast Forced Induction 15 02-20-2009 01:38 PM
Whats Wrong With This Ghetto Turbo Setup? hondamidnighter Forced Induction 23 08-09-2008 10:20 PM
HUGE turbo corvetteguy Members' Lounge 33 05-31-2005 07:28 PM
91 Turbo Mazda MX-6 (only $1500) dis crx guy Vehicles: For Sale/Trade/Wanted 11 10-27-2004 02:14 AM
Turbo parts, tires and tire stuff, and more civicrydah Parts: For Sale/Trade/Wanted 1 11-07-2003 12:44 PM


All times are GMT -5. The time now is 12:33 AM.


Powered by vBulletin® Version 3.7.x
Copyright ©2000 - 2009, Jelsoft Enterprises Ltd.
SEO by vBSEO
© 2001-2009 HondaSwap.com
One of the largest message boards on the web !  | a SkeyMedia Network site

Advertise on Hondaswap.com