How to build for low end power?
Dec 3, 2004, 08:29 AM
#1
How to build for low end power?
I would like to hear some opinions on how you would build a budget daily driver (20k mi. a year) to maximize quick spool and lower to mid range power.
Basicaly on the street if you have open exaust and your reving up to 7k, pretty much everyone is gonna know your going for it.
I'm willing to sacrifice power past 6k to keep it super quiet and be able to raise hell without attracting too much attention.
Obviously a stroker is the right answer but not for me yet.
would you....
-keep stock turbo? TME turbo, maybe with evo8 housing? (9.5?)
-keep stock exaust mani? equal length? I've read conflicting info concerning quicker spool, low end , high end gains?
-2.5" o2 and dp to 3" back, or 3" from turbo back?
keep stock cams? is it true stck cams will make the most low end torque?
-How would you tune?
Please no flaming, I fully realize and dig what this car is, why it is and where it came from but... I'm looking for a small-block v8/ STI type of power curve or at least in that direction without increasing displacment.
Basicaly on the street if you have open exaust and your reving up to 7k, pretty much everyone is gonna know your going for it.
I'm willing to sacrifice power past 6k to keep it super quiet and be able to raise hell without attracting too much attention.
Obviously a stroker is the right answer but not for me yet.
would you....
-keep stock turbo? TME turbo, maybe with evo8 housing? (9.5?)
-keep stock exaust mani? equal length? I've read conflicting info concerning quicker spool, low end , high end gains?
-2.5" o2 and dp to 3" back, or 3" from turbo back?
keep stock cams? is it true stck cams will make the most low end torque?
-How would you tune?
Please no flaming, I fully realize and dig what this car is, why it is and where it came from but... I'm looking for a small-block v8/ STI type of power curve or at least in that direction without increasing displacment.
Dec 3, 2004, 09:19 AM
#2
This has been done rather nicely by one forum member, but you should be advised that you WILL need a means of dealing with the tendency for preignition at low rpm. This is best achieved through MeOH/water injection.
* HKS 264 cams, advanced +2/+2 or even +3/+3 (advanced) - This will cause the turbo to begin spooling around 2500rpm, and will probably deliver at least as much idle vacuum as the stock cams = butter smooth idle quality. These cams most definitely deliver better torque than the factory cams.
* Tubular exhaust manifold - This will give a torque bump over the factory manifold, smack in the midrange.
* The TME turbo will deliver more midrange torque, and if you go with the full turbo (Ti internals), it will spool a little earlier than just swapping the hotside.
* Full 3" exhaust - A smaller exhaust will not necessarily perform better on the low end, and will reduce power on the top. Some exhausts are most certainly quieter than others, perform a search.
* Methanol/Water Injection - This is important if you are going to run the above setup and cam timing. It is a much more practical alternative to running race fuel constantly.
* Tuning - The P2 flash is a good start, but you will need revised fuel and spark settings to suit this specific configation. You will most certainly want dyno tuning. You will either need an on-the-spot reflash at the dyno, or a suitable aftermarket device (e.g. Xede).
With the above, you will generate a sizable midrange punch with a seamless transition to boost, and have a broad, flat power band from 2500-7500 rpm.
* HKS 264 cams, advanced +2/+2 or even +3/+3 (advanced) - This will cause the turbo to begin spooling around 2500rpm, and will probably deliver at least as much idle vacuum as the stock cams = butter smooth idle quality. These cams most definitely deliver better torque than the factory cams.
* Tubular exhaust manifold - This will give a torque bump over the factory manifold, smack in the midrange.
* The TME turbo will deliver more midrange torque, and if you go with the full turbo (Ti internals), it will spool a little earlier than just swapping the hotside.
* Full 3" exhaust - A smaller exhaust will not necessarily perform better on the low end, and will reduce power on the top. Some exhausts are most certainly quieter than others, perform a search.
* Methanol/Water Injection - This is important if you are going to run the above setup and cam timing. It is a much more practical alternative to running race fuel constantly.
* Tuning - The P2 flash is a good start, but you will need revised fuel and spark settings to suit this specific configation. You will most certainly want dyno tuning. You will either need an on-the-spot reflash at the dyno, or a suitable aftermarket device (e.g. Xede).
With the above, you will generate a sizable midrange punch with a seamless transition to boost, and have a broad, flat power band from 2500-7500 rpm.
Dec 3, 2004, 11:35 AM
#3
Thanks for the info ^ much appreciated and much to learn!
Any ideas on max torque @ the lowest rpm achieved on pump gas? Water/alcohol inj scares me.
I just read the RNR 2.4l gt35 thread !!!!
and the TME turbo results thread as well. good stuff.
Any ideas on max torque @ the lowest rpm achieved on pump gas? Water/alcohol inj scares me.
I just read the RNR 2.4l gt35 thread !!!!
and the TME turbo results thread as well. good stuff.
Dec 3, 2004, 11:43 AM
#4
HEAT,
in the form of "exhaust gas velocity" determines your torque characteristic. The faster you make your exhaust gasses reach your turbo (smaller diameter is better b/c it retains the heat) and keeping those gasses hot as they exit the tail pipe is the key.
High EGT's are
as long as you protect the turbo, oil pan, etc...
in the form of "exhaust gas velocity" determines your torque characteristic. The faster you make your exhaust gasses reach your turbo (smaller diameter is better b/c it retains the heat) and keeping those gasses hot as they exit the tail pipe is the key.
High EGT's are
as long as you protect the turbo, oil pan, etc...
Dec 3, 2004, 12:01 PM
#5
If you want to do it without wasting money I would do this:
264 cams
lower ic pipe
O2 Housing
3" Turboback with cat delete
open intake (HKS RS or Injen)
manual boost controller
ECU flash from TurboTrix (preferred) or Works. A piggyback or standalone is a complete waste for any setup using a stock turbo or a derivation of it.
If you want to go the "overboard" step, add the Ti internal 10.5 turbo. The 10.5 housing upgrade is a nice and relatively cheap alternative as well.
For less than $1.5K I can have you outrunning guys who have spent 4K on their cars. I do it all the time.
BTW, the BIGGER your piping AFTER the turbo, the better. There is no such thing as too big on a turbo car for torque or HP. This is not a NA car. Basically, just get out of the turbo's way!
264 cams
lower ic pipe
O2 Housing
3" Turboback with cat delete
open intake (HKS RS or Injen)
manual boost controller
ECU flash from TurboTrix (preferred) or Works. A piggyback or standalone is a complete waste for any setup using a stock turbo or a derivation of it.
If you want to go the "overboard" step, add the Ti internal 10.5 turbo. The 10.5 housing upgrade is a nice and relatively cheap alternative as well.
For less than $1.5K I can have you outrunning guys who have spent 4K on their cars. I do it all the time.
BTW, the BIGGER your piping AFTER the turbo, the better. There is no such thing as too big on a turbo car for torque or HP. This is not a NA car. Basically, just get out of the turbo's way!
Last edited by EVOTEXAS; Dec 3, 2004 at 12:04 PM.
Dec 3, 2004, 12:02 PM
#6
Originally Posted by 4-BNGR
HEAT,
in the form of "exhaust gas velocity" determines your torque characteristic. The faster you make your exhaust gasses reach your turbo (smaller diameter is better b/c it retains the heat) and keeping those gasses hot as they exit the tail pipe is the key.
High EGT's are as long as you protect the turbo, oil pan, etc...
in the form of "exhaust gas velocity" determines your torque characteristic. The faster you make your exhaust gasses reach your turbo (smaller diameter is better b/c it retains the heat) and keeping those gasses hot as they exit the tail pipe is the key.
High EGT's are
as long as you protect the turbo, oil pan, etc...Is there a balance between better flow (larger diameter) and better heat retention/ less exspansion (smaller diameter)?
I have read all the debates on exhaust diameter and it seemed to resolve with bigger = better. UNLESS your using the stck o2 (2.5) and bolting it up to a 3"dp in wich case the expanding gases could create turbulence and more resulting back pressure.
Dec 3, 2004, 12:40 PM
#7
Originally Posted by wingless
How would you physically execute this?? you mean wrapped/coated header? 2.5"dp?
Is there a balance between better flow (larger diameter) and better heat retention/ less exspansion (smaller diameter)?
I have read all the debates on exhaust diameter and it seemed to resolve with bigger = better. UNLESS your using the stck o2 (2.5) and bolting it up to a 3"dp in wich case the expanding gases could create turbulence and more resulting back pressure.
Is there a balance between better flow (larger diameter) and better heat retention/ less exspansion (smaller diameter)?
I have read all the debates on exhaust diameter and it seemed to resolve with bigger = better. UNLESS your using the stck o2 (2.5) and bolting it up to a 3"dp in wich case the expanding gases could create turbulence and more resulting back pressure.
It is a misconception that larger diameter piping "flows" better than smaller. Flow is heat. Too large a diameter may cause "turbulance" in the exhaust system, which compromises power. The most "efficient/powerful" exhaust is one that flows best. Bigger diameter exhaust make more power "bigger is better theory" when the exhaust gasses are optimally hot to make optimal flow (usually at a higher rpm). This is making power "up top". The higher your rpm, logically the faster the car is travelling... Gasses on a smaller diameter exhaust become hotter sooner than a larger exhaust, and at lower rpm, thus allowing for torque to be evident sooner than on a larger diameter exhaust. These gasses reach the turbo faster. I know faster is relative, but physics is physics.
The exhaust's diameter should be uniform to prevent turbulance. Higher EGT's also come at the expense of your engine and turbo...
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Dec 3, 2004, 12:42 PM
#8
Originally Posted by wingless
Any ideas on max torque @ the lowest rpm achieved on pump gas? Water/alcohol inj scares me.
If you intend to get power very early on, you'll have to be prepared to do what it takes to support it. Otherwise, just follow the proven performance logic and be happy with it (just about everyone is).
I run 21psi with a mbc with taper to 19psi, no problem.
Dec 4, 2004, 07:04 AM
#13
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Originally Posted by EVOTEXAS
If you want to do it without wasting money I would do this:
264 cams
lower ic pipe
O2 Housing
3" Turboback with cat delete
open intake (HKS RS or Injen)
manual boost controller
ECU flash from TurboTrix (preferred) or Works. A piggyback or standalone is a complete waste for any setup using a stock turbo or a derivation of it.
If you want to go the "overboard" step, add the Ti internal 10.5 turbo. The 10.5 housing upgrade is a nice and relatively cheap alternative as well.
For less than $1.5K I can have you outrunning guys who have spent 4K on their cars. I do it all the time.
BTW, the BIGGER your piping AFTER the turbo, the better. There is no such thing as too big on a turbo car for torque or HP. This is not a NA car. Basically, just get out of the turbo's way!
264 cams
lower ic pipe
O2 Housing
3" Turboback with cat delete
open intake (HKS RS or Injen)
manual boost controller
ECU flash from TurboTrix (preferred) or Works. A piggyback or standalone is a complete waste for any setup using a stock turbo or a derivation of it.
If you want to go the "overboard" step, add the Ti internal 10.5 turbo. The 10.5 housing upgrade is a nice and relatively cheap alternative as well.
For less than $1.5K I can have you outrunning guys who have spent 4K on their cars. I do it all the time.
BTW, the BIGGER your piping AFTER the turbo, the better. There is no such thing as too big on a turbo car for torque or HP. This is not a NA car. Basically, just get out of the turbo's way!
Dec 4, 2004, 07:11 AM
#14
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It is no misconception that a larger pipe will flow better than a smaller pipe. This is simple fluid dynamics. A larger pipe will create less friction loss and allow more flow. Now having said that larger is not always better as you want a balance between low back pressure and high exhaust gas velocity to spool the turbo. Obviously with a larger pipe you will be more likely to lose heat and insulation could be a critical factor. Like I said though its a balance. If high exhaust gas velocity was the only critical parameter then we would have exhaust manifolds that looked like straws. And for the record you experience turbulent flow quicker in a smaller pipe with higher gas velocity than you will in a bigger pipe.