LS Turbo questions
11-27-2010, 09:33 PM
#1
n00b
Thread Starter
Join Date: Jan 2010
Location: Toronto
Posts: 65
LS Turbo questions
I plan to go LS Turbo aiming at 300 hp at first and moving up to 450 ish
Would i only need to build the block or would i also have to build the head aswell
Also what would the best transmission be for this kind of build, the gsr lsd transmission or the ls-quaife transmission, cuz i hear longer gears is good but also hear too long of a gear just causes you to spool longer or something like that
Would i only need to build the block or would i also have to build the head aswell
Also what would the best transmission be for this kind of build, the gsr lsd transmission or the ls-quaife transmission, cuz i hear longer gears is good but also hear too long of a gear just causes you to spool longer or something like that
11-27-2010, 11:23 PM
#2
Your best bet is research. A good understanding of turbo basics is the best starting point and a good framework for a build.
I think you have the right idea in setting a goal, now what's left is the technicals, piecing together your turbo setup and engine setup.
Depending on the type of turbo system you run and the power you make you'll need to consider the transmission to put you in the right powerband. It's hard to generalize and say that a specific transmission will put you where you need to be on the upshift. A lot of factors come into play.
Some useful links for your reading enjoyment:
www.homemadeturbo.com
http://www.beesandgoats.com/boostfaq/g2icturbo.html
http://www.honda-tech.com/showthread.php?t=1263795
I think you have the right idea in setting a goal, now what's left is the technicals, piecing together your turbo setup and engine setup.
Depending on the type of turbo system you run and the power you make you'll need to consider the transmission to put you in the right powerband. It's hard to generalize and say that a specific transmission will put you where you need to be on the upshift. A lot of factors come into play.
Some useful links for your reading enjoyment:
www.homemadeturbo.com
http://www.beesandgoats.com/boostfaq/g2icturbo.html
http://www.honda-tech.com/showthread.php?t=1263795
11-28-2010, 12:02 AM
#3
Um ok, well when you get to 300whp, get bigger brakes and suspension. Just an idea...because it seems like people don't understand how much power 300whp is in a car that weighs under a ton.
Now regarding the build, you can keep a stock head, just need to size the turbo to keep you in lower rpms, since head will limit your rev limit. Also, seems like regardless of how much money you spend at a machine shop, the ls head will never flow as well as let's say type R (that is true unless you go full race head porting with valves that are a lot bigger). So the head will either way be a restriction. Mind you that can be fixed with few extra psi of boost. Starting off with a good set of rods and low compression pistons would be key. Now I would recommend few more things for a 450whp setup so might aswell get everything done from the beginning. JE rods would be my choice but there are many brands to choose from, also pistons in 8.5:1-9:1 cpr would be key. Lower is better for later, the only downside is that the car will run like a bag of...until boost kicks in. Getting the whole rotating assembly balanced would be a good idea, replacing crank/rod bearings I would consider a must also. Oil cooler would be a good investment and a huge exhaust will always help in turbo application. And I mean 3" atleast!
Now for turbo sizing, you got some math to do, from what I remember the 57 trim super60 or t3/t4 would work well. Also garrett gt3276 would put you where you want. But that's just going off my memory (which tends to fail in the midle of the night).
Just an question, do you know how much 450whp actually is? Its not fun to street drive since the clutch will not be forgiving due to the clamping force and material, and at such power expect to break parts a lot quicker. When you think about it, a car that originally had 140hp (130whp) goes up to 450whp which is more than tripple, it cannot be as reliable as it was. I say get to 300 and hold on to the wheel...and enjoy the uncontrollable wheelspin.
Oh and regarding transmissions, I would say stick with ls trans and install lsd. Highway driving at 4k rpm and in boost wouldn't be efficient nor necessary. Plus the added torque in all gears would result in even more uncontrollable wheel spin and nonstop shifting. Where as ls trans would allow you keep going in one gear for longer in boost.
Now regarding the build, you can keep a stock head, just need to size the turbo to keep you in lower rpms, since head will limit your rev limit. Also, seems like regardless of how much money you spend at a machine shop, the ls head will never flow as well as let's say type R (that is true unless you go full race head porting with valves that are a lot bigger). So the head will either way be a restriction. Mind you that can be fixed with few extra psi of boost. Starting off with a good set of rods and low compression pistons would be key. Now I would recommend few more things for a 450whp setup so might aswell get everything done from the beginning. JE rods would be my choice but there are many brands to choose from, also pistons in 8.5:1-9:1 cpr would be key. Lower is better for later, the only downside is that the car will run like a bag of...until boost kicks in. Getting the whole rotating assembly balanced would be a good idea, replacing crank/rod bearings I would consider a must also. Oil cooler would be a good investment and a huge exhaust will always help in turbo application. And I mean 3" atleast!
Now for turbo sizing, you got some math to do, from what I remember the 57 trim super60 or t3/t4 would work well. Also garrett gt3276 would put you where you want. But that's just going off my memory (which tends to fail in the midle of the night).
Just an question, do you know how much 450whp actually is? Its not fun to street drive since the clutch will not be forgiving due to the clamping force and material, and at such power expect to break parts a lot quicker. When you think about it, a car that originally had 140hp (130whp) goes up to 450whp which is more than tripple, it cannot be as reliable as it was. I say get to 300 and hold on to the wheel...and enjoy the uncontrollable wheelspin.
Oh and regarding transmissions, I would say stick with ls trans and install lsd. Highway driving at 4k rpm and in boost wouldn't be efficient nor necessary. Plus the added torque in all gears would result in even more uncontrollable wheel spin and nonstop shifting. Where as ls trans would allow you keep going in one gear for longer in boost.
11-28-2010, 06:49 AM
#4
n00b
Thread Starter
Join Date: Jan 2010
Location: Toronto
Posts: 65
well my initial plan was to get the gt35 turbo but i guess that won't be done
I've never experienced 450 hp but i was planning to move up slowly from 300 if i wanted to as an option but i'm pretty sure i'll be happy at 300 hp.
How would i know if my ls transmission gears are worn out cuz right now my clutch isn't working properly and i need to replace it but i was wondering whether to go gsr or stick to the ls with lsd unless my gears have gone bad, which i would want to last for 300hp.
Btw thanks a lot for your input guys really appreciate it.
I've never experienced 450 hp but i was planning to move up slowly from 300 if i wanted to as an option but i'm pretty sure i'll be happy at 300 hp.
How would i know if my ls transmission gears are worn out cuz right now my clutch isn't working properly and i need to replace it but i was wondering whether to go gsr or stick to the ls with lsd unless my gears have gone bad, which i would want to last for 300hp.
Btw thanks a lot for your input guys really appreciate it.
11-29-2010, 04:30 PM
#7
n00b
Thread Starter
Join Date: Jan 2010
Location: Toronto
Posts: 65
Oh and regarding transmissions, I would say stick with ls trans and install lsd. Highway driving at 4k rpm and in boost wouldn't be efficient nor necessary. Plus the added torque in all gears would result in even more uncontrollable wheel spin and nonstop shifting. Where as ls trans would allow you keep going in one gear for longer in boost.
I also read that an ls tranny jus causes the turbo to spool longer so you jus accelerate slower is that true? I keep getting mixed information so i am not able to make a good decision
11-29-2010, 06:22 PM
#8
Well yes, with gsr transmission you will be quicker...in a sense. You will have a better mechanical advantage, more power in 1.x:1 gear ratio speeds (where x is more than 0), your engine output power will stay the same so dont get that confused. My personal opinion, i would go with ls and not gsr, got tired of screaming down the highway at 4k rpm with my old b16 transmission, and with 300whp, the slight decrease in power would be hardly noticeable. Hell even with the torqueless b20 i got, going from b16 to ls transmission, yes i noticed a difference but its not major. Though you dont rev up as quick, you still pull hard and have no problems keeping up with cars i did when i had the b16 trans. mind you its not stock...when a car is really struggling to accelerate, the gear ratios will really make a difference, but when you have some real power flowing in, its not such a big deal.
11-30-2010, 09:29 AM
#10
Moderator
Join Date: May 2010
Location: Where my car is.
Posts: 724
To the OP:
To safely make 300whp with the potential to make more, these are my recommendations;
-It makes sense to swap to a vtec head. You'll make more power with the same amount of boost then you will with a non-vtec head. The vtec heads flow much better. (B16, B18C1/C5/C). Doing a vtec head swap there are a few extra steps you'll have to take to make it work. Nothing major but there are DIY's for this all over the net. You need a timing belt and water pump from the engine the head came off of as well as a slight mod to the oil pump, among a few other things.
-If you ever want to make more power you'll want to install a set of mild (not extreme) NA cams with adjustable cam gears to decrease the overlap in the cam timing, or install a set of forced induction cams which are designed to work with forced induction applications and minimizes overlap.
-To make it last, you'll want stronger rods and forged pistons with slightly lower compression. ARP rod bolts and head studs are a must. You should also have the whole rotating assembly balanced.
-Properly size the turbo!!! I can't stress this enough. This is the difference between having power available 90% of the time, through most of the rpm range or power available 20% of the time, only in the high rpm range. Just because you want quite a bit of power doesn't mean you need a gigantic turbo that doesn't spool until 5000rpm+. That is useless. What you need to do is do some rough calculations and estimates to see how much air-flow you'll need to make the power you want to make. Then look at the compressor maps of various turbos to see which will provide enough airflow to match throughout most of the engine's rpm range while keeping within the turbo's efficiency range. Example: On our autocross car (87 toyota MR2) we're using an oem turbo from a stock subaru WRX. While some will say it's a tad small for the WRX application (2.0L engine), matched to the 1.6L in the MR2 it is capable of sustaining 25psi from 3000rpm to the limiter at 7500rpm. We were running only 13-15psi and it was probably making between 250-275whp. So as you can see, you don't need a huge, slow-spooling turbo, you need one that is properly sized for the application. Most people go too big, even for very mild builds (200-250whp). A T3 50 trim or similar should be more than enough. A GT35, imo, is too big for this application. Best guess is most builds I've seen with LS-vtec turbo motors around the 300whp mark, are only running about 10-15psi, depending on the turbo and the tune. If 10-15 psi is all you need to reach your power goal, then size a turbo that will be capable of flowing enough air within it's effeciency range to provide your engine with about 20-25psi at the highest rpm allowing for the widest boost range possible.
-Tuning. This is also extremely important. You either need a stand-alone ecu system like megasquirt (just as good as AEM EMS or anyother super-expesive, over-rated stand alone system, but for a tiny fraction of the cost...lol) or a chipped OBDI ecu with OBDII-OBDI conversion harness. Have it tuned by someone who is extremely knowledgable and has a lot of experience in the field (and with hondas), like HiVelocity tuning etc...
-I'd go with the taller-geared LS trans. With a properly sized turbo, you won't be droping out of boost range much and you'll spin less in the lower gears. If the gears are too short, they're just useless. You'll have enough trouble trying to put down 300whp through the front wheels as it is...lol. Not that fuel mileage is going to be important with a build like this, but an ls trans will allow you to get better mileage. With tuning, turbo engines can be very good on gas. Not all hope is lost. haha.
-Choose a good bov. Don't choose based on sound. The sound it makes is irrelevent. It's function is what is important. You don't want it to chatter. The chattering sounds cool but what you're hearing is compressor surge. That can kill a turbo quickly. What you want is for it to open the instant you lift off the throttle and stay open until you get back on it. It should cleanly, smoothly, quickly and efficiently vent the compressed air from the charge pipe. It is also best to locate it on the charge pipe up near the throttle body as to keep the volume of air in the pipes moving towards the engine and not have to change direction and flow backwards towards the turbo.
A few extra things to note: FWD cars under ~2800lbs can only really effectively make use of about 250whp, depending on the chassis setup and tire choice. Anything more is useless through the first 3 gears. Being realistic, you can safely boost what you have to between 200-250whp with stock internals (using ARP rod bolts and head studs), which is nearly twice what you have now and is plenty for the street/track and will cost you a lot less than building it for 300whp+. And yeah, upgrade your brakes, suspension and tires. If you're going to make the car that much faster, you must also be able to stop faster and handle better.
To safely make 300whp with the potential to make more, these are my recommendations;
-It makes sense to swap to a vtec head. You'll make more power with the same amount of boost then you will with a non-vtec head. The vtec heads flow much better. (B16, B18C1/C5/C). Doing a vtec head swap there are a few extra steps you'll have to take to make it work. Nothing major but there are DIY's for this all over the net. You need a timing belt and water pump from the engine the head came off of as well as a slight mod to the oil pump, among a few other things.
-If you ever want to make more power you'll want to install a set of mild (not extreme) NA cams with adjustable cam gears to decrease the overlap in the cam timing, or install a set of forced induction cams which are designed to work with forced induction applications and minimizes overlap.
-To make it last, you'll want stronger rods and forged pistons with slightly lower compression. ARP rod bolts and head studs are a must. You should also have the whole rotating assembly balanced.
-Properly size the turbo!!! I can't stress this enough. This is the difference between having power available 90% of the time, through most of the rpm range or power available 20% of the time, only in the high rpm range. Just because you want quite a bit of power doesn't mean you need a gigantic turbo that doesn't spool until 5000rpm+. That is useless. What you need to do is do some rough calculations and estimates to see how much air-flow you'll need to make the power you want to make. Then look at the compressor maps of various turbos to see which will provide enough airflow to match throughout most of the engine's rpm range while keeping within the turbo's efficiency range. Example: On our autocross car (87 toyota MR2) we're using an oem turbo from a stock subaru WRX. While some will say it's a tad small for the WRX application (2.0L engine), matched to the 1.6L in the MR2 it is capable of sustaining 25psi from 3000rpm to the limiter at 7500rpm. We were running only 13-15psi and it was probably making between 250-275whp. So as you can see, you don't need a huge, slow-spooling turbo, you need one that is properly sized for the application. Most people go too big, even for very mild builds (200-250whp). A T3 50 trim or similar should be more than enough. A GT35, imo, is too big for this application. Best guess is most builds I've seen with LS-vtec turbo motors around the 300whp mark, are only running about 10-15psi, depending on the turbo and the tune. If 10-15 psi is all you need to reach your power goal, then size a turbo that will be capable of flowing enough air within it's effeciency range to provide your engine with about 20-25psi at the highest rpm allowing for the widest boost range possible.
-Tuning. This is also extremely important. You either need a stand-alone ecu system like megasquirt (just as good as AEM EMS or anyother super-expesive, over-rated stand alone system, but for a tiny fraction of the cost...lol) or a chipped OBDI ecu with OBDII-OBDI conversion harness. Have it tuned by someone who is extremely knowledgable and has a lot of experience in the field (and with hondas), like HiVelocity tuning etc...
-I'd go with the taller-geared LS trans. With a properly sized turbo, you won't be droping out of boost range much and you'll spin less in the lower gears. If the gears are too short, they're just useless. You'll have enough trouble trying to put down 300whp through the front wheels as it is...lol. Not that fuel mileage is going to be important with a build like this, but an ls trans will allow you to get better mileage. With tuning, turbo engines can be very good on gas. Not all hope is lost. haha.
-Choose a good bov. Don't choose based on sound. The sound it makes is irrelevent. It's function is what is important. You don't want it to chatter. The chattering sounds cool but what you're hearing is compressor surge. That can kill a turbo quickly. What you want is for it to open the instant you lift off the throttle and stay open until you get back on it. It should cleanly, smoothly, quickly and efficiently vent the compressed air from the charge pipe. It is also best to locate it on the charge pipe up near the throttle body as to keep the volume of air in the pipes moving towards the engine and not have to change direction and flow backwards towards the turbo.
A few extra things to note: FWD cars under ~2800lbs can only really effectively make use of about 250whp, depending on the chassis setup and tire choice. Anything more is useless through the first 3 gears. Being realistic, you can safely boost what you have to between 200-250whp with stock internals (using ARP rod bolts and head studs), which is nearly twice what you have now and is plenty for the street/track and will cost you a lot less than building it for 300whp+. And yeah, upgrade your brakes, suspension and tires. If you're going to make the car that much faster, you must also be able to stop faster and handle better.
11-30-2010, 12:27 PM
#11
Moderator
Join Date: May 2010
Location: Where my car is.
Posts: 724
Forgot to add, you'll need to upgrade the fuel system as well. You'll want to install a 255lph fuel pump, adjustable fuel pressure regulator and larger injectors.
If you're going for 200-250whp, DSM 440cc injectors should be enough. If you're going for 300whp+, DSM's won't cut it, you'll need bigger ones. And don't crank up the fuel pressure to compensate for inadequate injectors.
If you're going for 200-250whp, DSM 440cc injectors should be enough. If you're going for 300whp+, DSM's won't cut it, you'll need bigger ones. And don't crank up the fuel pressure to compensate for inadequate injectors.
11-30-2010, 04:51 PM
#12
n00b
Thread Starter
Join Date: Jan 2010
Location: Toronto
Posts: 65
wow this was extremely thorugh
so if i were to go 200-250 hp would it still be a good idea to go ls/vtec cuz i heard ls/vtec is unreliable but others say its reliable if done properly
what are your opinions on that?
so if i were to go 200-250 hp would it still be a good idea to go ls/vtec cuz i heard ls/vtec is unreliable but others say its reliable if done properly
what are your opinions on that?
11-30-2010, 11:06 PM
#13
^^OMG if another person says b20v/lsv is unreliable, i shall snap!
Reason why they are unreliable, is because people slap the vtec heads on old beaten blocks, set rev limit to 9k and without no tune or **** tune start beating the car.
In reality, if your block is healthy and you don't rev **** out of it, it will be reliable as any other honda engine. Stay within 7.5k rev limit or so, and you will have absolutely no problems.
Few more key things, make sure you got enough oil flowing through [some oil pumps may require disassembly to remove a washer on a spring to increase psi] and use gsr water pump/timing belt. You do all that and throw a good tune along, you will be loving life with less boost and same power.
Reason why they are unreliable, is because people slap the vtec heads on old beaten blocks, set rev limit to 9k and without no tune or **** tune start beating the car.
In reality, if your block is healthy and you don't rev **** out of it, it will be reliable as any other honda engine. Stay within 7.5k rev limit or so, and you will have absolutely no problems.
Few more key things, make sure you got enough oil flowing through [some oil pumps may require disassembly to remove a washer on a spring to increase psi] and use gsr water pump/timing belt. You do all that and throw a good tune along, you will be loving life with less boost and same power.
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