TURBO FOR LS ENGINE ?

[antz]

Now after reading that an ls motor has a more ideal compression ratio for boost than a b16 I was wondering what I would have to do to rebuild the engine so that it runs right I always heard its not good to boost high mileage engines should i rebuild the engine and put some apr bolts and a better head gasket? Some let me know wud up ...?

[mrchris1979]

It's best to know as much as you can how your motor is internally. A good start is to do a compression test to see how your cylinders are. A large margin of difference between any cylinder is a sure sign of trouble for boost in the future. Also inspect your spark plugs and read their condition after a few wide throttle passes. Put a new set in there, drive a litttle bit until the motor gets up to normal operating temp. and do a wide throttle pass from 1st to 4th gear. Remove the plugs and inspect them oil fouling, extremely rich or lean conditions. A Helms or Chiltons manual will give you a general idea of how to read your spark plugs or looking online is another good resource. Remember that this is a DIY way of determining how your motor is performing generally so in no means is this the professional way to do this. Otherwise take it to Tobi at TC's Performance and he can come up with something for you before you boost. A rebuild motor is of course the best way to start any project if you have the cash to do it. What I did on my nitrous D16 with 120,000 miles was replace the head gasket and upgraded to ARP studs because I did not know the condition of the headgasket anyway, plus I knew that this area was weak from the high milage. I Did the compression test, check the plugs and everything checked out good. I was looking into a rebuild but I thought if the motor was going to give out, at least the rebuild was on the plan. We'll, 16 bottles later with a 50 shot and after a whole season in Bandimere, test tuning and drag racing, the motor never gave up. Only problem now is some oil burning from worn piston rings, but Nitrous is a lot harder on a motor anyway. But still, the piston rings just needed to be replaced. A full rebuild was not neccessary. So in my opinion, if you have the cash, rebuild the motor and boost it. If not, replacing the head gasket and upgrading to ARP studs is a good start. Also, start will low boost, keep a good tune and always check up on your motor. At least for now, you can get some satisfaction with a boosted LS before it gives up on you.....If it gives up.



Now after reading that an ls motor has a more ideal compression ratio for boost than a b16 I was wondering what I would have to do to rebuild the engine so that it runs right I always heard its not good to boost high mileage engines should i rebuild the engine and put some apr bolts and a better head gasket? Some let me know wud up ...?

[Aracheon]

Excellent reply. :)

[redb20teg]

Excellent reply. :)

YES! very nice indeed.

[Skaterkid]

Stay away from the check valve on the MAP sensor though. Bad idea. Stu's motor was doing fine till he did that

[Weston]

Yeah, your fuel setup should be one that still uses a MAP sensor to calculate the amount of fuel to inject, just like a modern factory turbo car. Stay far away from FMU's (or anything that greatly increases fuel pressure) and check valves / Missing Links; they are ghetto. The DSM 450 + VAFC setup works very well when done properly, and a handy side effect is that it also prevents the boost CEL (until you run somewhere over 10 psi). I've been running this for a year and a half now, with far more abuse than 99% of boosted Hondas (or any car) will ever see... the only problem the engine developed was a leaky head gasket, which wasn't a big deal, and it was the result of some pretty extreme abuse. I installed a new head gasket and ARP head studs, and now the problem is solved and is far less likely to come back. I did notice a little upper cylinder wall scoring, most likely from one of the times that I road raced it while overheating, but the compression is still good so I don't care. I'll be running more boost this season... :)

[mrchris1979]

Definitely Say no to ghetto. Check valves and FMU are old school set-ups that is suprisingly still used by a lot of boosted Hondas. Its cheap and it works but for a little more cash, a used VAFC, 450 injectors and an MSD BTM will give anyone a better fuel/timing set-up that produces a smoother boost transition and is tunable up to 11 PSI on a stock MAP. Anyone boosting more than 11psi on a stock block should consider investing in a standalone anyway. By the way Weston, how much HP did you end up with on your Turbo LS and if you got a 1/4 time on it? I just swapped a B18c1 on my CRX and getting ready to boost it using a T3/T4, FMIC, 2.5" DP/exhaust and using the VAFC, MSD and 450's. I've been boosting D-series motors for a while and this is my first B project. I should expect more because of VTEC but I just want to get an idea of what this thing will do.



Yeah, your fuel setup should be one that still uses a MAP sensor to calculate the amount of fuel to inject, just like a modern factory turbo car. Stay far away from FMU's (or anything that greatly increases fuel pressure) and check valves / Missing Links; they are ghetto. The DSM 450 + VAFC setup works very well when done properly, and a handy side effect is that it also prevents the boost CEL (until you run somewhere over 10 psi). I've been running this for a year and a half now, with far more abuse than 99% of boosted Hondas (or any car) will ever see... the only problem the engine developed was a leaky head gasket, which wasn't a big deal, and it was the result of some pretty extreme abuse. I installed a new head gasket and ARP head studs, and now the problem is solved and is far less likely to come back. I did notice a little upper cylinder wall scoring, most likely from one of the times that I road raced it while overheating, but the compression is still good so I don't care. I'll be running more boost this season... :)

[Weston]

I'm at 236 whp and 226 tq on 9 psi and a small T3 (low lag road racing build). I ran 14.4 at Bandimere on my old exhaust (2.25", which is smaller than the turbo's exhaust outlet), so I'm expecting high 13's or real low 14's now. It's not at all a drag setup though... my goal with this has been lots of mid range torque and low lag for road course racing. The stock LS cams and intake manifold cause the torque to really drop off above 5200 rpm (just like stock), so the peak HP isn't real high, but the mid range torque is good and that's what I'm going for. A turbo GS-R will make significantly more peak HP, but of course that comes at the price of the torque powerband being much higher... should be good for drag.

[Zach]

couldnt you just put the edelbrock intake manifold and throttle body to cure that problem?^^^ I have heard that they increase midrange and peak power and torque.

[rmcdaniels]

couldnt you just put the edelbrock intake manifold and throttle body to cure that problem?^^^ I have heard that they increase midrange and peak power and torque.
At the expense of low-end power and torque. Most of the guys I know with the Edelbrock manifold use it for drag racing.

[Weston-work]

Exactly... things like that don't really "make" power, they just move it from one place to another. They only increase peak HP because that's just an indication of how much top end the engine has; it comes at the cost of ending up with less HP and torque down low. I'm currently making my peak torque from 4200 rpm to 5200 rpm and it works quite well for acceleration out of the turns, but in a drag race, I only really hit that powerband in 1st and 2nd gears (other gears just barely touch the end of it).

[Zach]

so what can you do to cure that? is there some kind of manifold that maximizes power throughout the powerband? or do they all just focus on one point in it?

[mrchris1979]

I'll be happy wih those numbers. I'll be using a Garrett T3/T4 .48/.60AR and max out at 10psi to keep it safe. The exhaust outlet is 2.5" but now I'm debating if I should use the 2.5"DP and flare it out to a 3" exhaust. I think that a 2.5" DP/ exhaust is good enough but I was given a few suggestions to open the pipe up as close to the turbo as possible. What do you all think I about this? Other than that, I''ve got a set of cam gears to use and may upgrade my intake manifold to an Edelbrock. I'll be putting everything together in next few weeks and I'll post my dyno results soon.


I'm at 236 whp and 226 tq on 9 psi and a small T3 (low lag road racing build). I ran 14.4 at Bandimere on my old exhaust (2.25", which is smaller than the turbo's exhaust outlet), so I'm expecting high 13's or real low 14's now. It's not at all a drag setup though... my goal with this has been lots of mid range torque and low lag for road course racing. The stock LS cams and intake manifold cause the torque to really drop off above 5200 rpm (just like stock), so the peak HP isn't real high, but the mid range torque is good and that's what I'm going for. A turbo GS-R will make significantly more peak HP, but of course that comes at the price of the torque powerband being much higher... should be good for drag.

[Weston]

so what can you do to cure that? is there some kind of manifold that maximizes power throughout the powerband? or do they all just focus on one point in it?

For the most part, there is one ideal RPM where it has peak effiency, so it will encourage peak torque to be made around that RPM. The GS-R engine has VTEC and dual intake runners to change the configuration on the fly, but unfortunately they are only used for simple switching between economy and performance, so it doesn't do us much good here. However, the iVTEC on newer Honda engines is more sophisticated and has decent potential.

I'll be happy wih those numbers. I'll be using a Garrett T3/T4 .48/.60AR and max out at 10psi to keep it safe. The exhaust outlet is 2.5" but now I'm debating if I should use the 2.5"DP and flare it out to a 3" exhaust. I think that a 2.5" DP/ exhaust is good enough but I was given a few suggestions to open the pipe up as close to the turbo as possible. What do you all think I about this? Other than that, I''ve got a set of cam gears to use and may upgrade my intake manifold to an Edelbrock. I'll be putting everything together in next few weeks and I'll post my dyno results soon.

I'm running a 2.5" downpipe and 2.5" high-flow cat into a 3" cat-back, and I'm pretty happy with it. Opening it up a lot will move power from low RPMs to high RPMs, because it reduces the flow velocity at low-mid RPMs while increasing the capacity for high RPM exhaust. Flow velocity is how fast the exhaust is coming out... the faster it goes, the more of a vacuum it will create behind it, and that works to suck the exhaust out of the engine and through the pipes. I'm a big fan of stepped exhausts... starting somewhat small near the engine and then moving up to larger piping by the time it gets to open air.

[mrchris1979]

Thanks for the input. The 3" catback is a good idea. Sucks that I just blew $300 bucks on a custom made 2.5" exhaust system and then I find Kteller's website who sells pre fitted 3" mandrel bent piping for CRX's which is $250 cheaper than what my muffler shop quoted me. Needless to say, I was not happy.

For the most part, there is one ideal RPM where it has peak effiency, so it will encourage peak torque to be made around that RPM. The GS-R engine has VTEC and dual intake runners to change the configuration on the fly, but unfortunately they are only used for simple switching between economy and performance, so it doesn't do us much good here. However, the iVTEC on newer Honda engines is more sophisticated and has decent potential.



I'm running a 2.5" downpipe and 2.5" high-flow cat into a 3" cat-back, and I'm pretty happy with it. Opening it up a lot will move power from low RPMs to high RPMs, because it reduces the flow velocity at low-mid RPMs while increasing the capacity for high RPM exhaust. Flow velocity is how fast the exhaust is coming out... the faster it goes, the more of a vacuum it will create behind it, and that works to suck the exhaust out of the engine and through the pipes. I'm a big fan of stepped exhausts... starting somewhat small near the engine and then moving up to larger piping by the time it gets to open air.