big single turbo vs twins
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Staging Lane
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big single turbo vs twins Is there a reason why there are more 8 second streets cars using a big single (88mm-94mm)turbo rather than using twins? Just wondering because over looking the forum, I see a lot more big single turbo f-bodys going 8's that are street cars, I've only seen a few twin turbo cars running that number, unless all the twin guys are not sharing there builds. Can someone help me out here?
Teching In
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From: Great White North
IMO There easier to fit as well as lot of classes only allow 1 which has pushed the development of these turbos being more efficient. So when doing a build you have a proven combination to go by.
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From: KS
Most people are looking at packaging, and twins typically cost more with the need for 2 of a couple different things. However a mindset that twins won't make the numbers would be as ignorant a statement as saying the earth is flat. Twins usually spool faster and will do the work. My car (small twins) is making boost crossing an intersection at 1/3 throttle. A lot of guys with big singles have trans brakes and 2 steps and still set at the line on the track for 2 seconds + waiting on the thing to build boost.
Most people are looking at packaging, and twins typically cost more with the need for 2 of a couple different things. However a mindset that twins won't make the numbers would be as ignorant a statement as saying the earth is flat. Twins usually spool faster and will do the work. My car (small twins) is making boost crossing an intersection at 1/3 throttle. A lot of guys with big singles have trans brakes and 2 steps and still set at the line on the track for 2 seconds + waiting on the thing to build boost.
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Most people are looking at packaging, and twins typically cost more with the need for 2 of a couple different things. However a mindset that twins won't make the numbers would be as ignorant a statement as saying the earth is flat. Twins usually spool faster and will do the work. My car (small twins) is making boost crossing an intersection at 1/3 throttle. A lot of guys with big singles have trans brakes and 2 steps and still set at the line on the track for 2 seconds + waiting on the thing to build boost.
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From: KS
I assume you are asking "what" like what do I mean about making boost. What I mean is about the time I'm crossing an intersection my car is show positive pressure. A couple lbs and it doesn't take WOT to get it.
Here is a quote that addresses the OP's thread. This guy, a sponsor, won't get the rolleyes comments that I get even though what I'm saying is true. I'll dig a little deeper where he made the same comment that I have about boost pulling away from a stop light. I do a lot of reading.
Here is a quote that addresses the OP's thread. This guy, a sponsor, won't get the rolleyes comments that I get even though what I'm saying is true. I'll dig a little deeper where he made the same comment that I have about boost pulling away from a stop light. I do a lot of reading.
The following thoughts and rambling is directed towards what I see as the majority of the street/strip turbo LS crowd. As a disclaimer, the following is my -opinion- but it is backed by experience. Oh yeah, and I don't sugar coat things.
First off, the same with anything, a turbo LS needs to be looked at as an entire, matched combination. Set your goals first and then decide on components that will allow you to reach those goals.
That being said, big compressor wheels and tiny turbines seem to be all the rage these days. Guess it makes for an affordable turbo. It also makes for sub-par performance.
If you've decided that you absolutely must use a 76mm compressor and a 12mm turbine
, really don't even bother with a "what cam should I use" thread because if you have money for a cam that will do absolutely nothing for you, it should be spent towards a turbo that is actually capable of efficiently making power.
Why does your car nose over at 5k? Chances are your turbo belongs in the dumpster or you have way too big of an engine for your current turbo. Want to make 950rwhp and 7000rpm with a PT7675? Run a 5.3. Want to spend more money on a 408 and max out the same turbo at 775rwhp and 5200rpm? Probably not, but people do it.
Not sure why but it seems many people shy away from twin setups. Twins absolutely cannot be beat in terms of a fun street car. Even an undersized pair of twins that make nearly instant boost will still outshine most similarly capable singles up top. I don't like lag so I always run twins. And I'm not talking logged boost VS wot, I'm talking about having driven countless amount of turbo cars and knowing the difference in feel when you roll on the gas of a single or a small set of similarly capable twins. Transient response is what you feel in normal every day driving and you get it in spades with a good twin setup.
Rear mount? Sure they can be fast at the strip as you have time to get the things online while you're bumping it in. As for a fun driving combination on the street? None that I've driven accomplish that. Wouldn't use it if it was given to me. (refer to, I don't like lag so I run twins/etc/etc)
Back to the cam thing. I'll use the cams we have available as examples because well, why not. I designed them and tuned them over the years so at least I can speak about them with experience.
TUO-216/216 114lsa. I would plan on bigger if I planned on over 700rwhp.
TU1-225/225 113lsa. I may consider a bigger cam if 950rwhp wasn't enough.
TU2-236/236 112.5lsa. If you have a combo capable of 1200rwhp and 7800rpm than this cam will work great.
Guess the point I'm trying to make on cams is that I think 90% of people cheap out on their turbo then over-cam the hell out of it thinking it will somehow compensate when in reality all you did was soften up the bottom end and midrange for no gains up top.
So, in closing, if you're building or planning a build on a turbo LS and your goal is to not be disappointed, THE most important thing to buy is a good turbocharger or turbochargers. Second is valvesprings. If you cheaped out on the turbo so you could buy more cubes, a different intake manifold, a different cam, a set of heads, a throttle body, an electric water pump, or even a torque converter, you've made a poor decision.
Rant over, let the flames begin
First off, the same with anything, a turbo LS needs to be looked at as an entire, matched combination. Set your goals first and then decide on components that will allow you to reach those goals.
That being said, big compressor wheels and tiny turbines seem to be all the rage these days. Guess it makes for an affordable turbo. It also makes for sub-par performance.
If you've decided that you absolutely must use a 76mm compressor and a 12mm turbine
, really don't even bother with a "what cam should I use" thread because if you have money for a cam that will do absolutely nothing for you, it should be spent towards a turbo that is actually capable of efficiently making power. Why does your car nose over at 5k? Chances are your turbo belongs in the dumpster or you have way too big of an engine for your current turbo. Want to make 950rwhp and 7000rpm with a PT7675? Run a 5.3. Want to spend more money on a 408 and max out the same turbo at 775rwhp and 5200rpm? Probably not, but people do it.
Not sure why but it seems many people shy away from twin setups. Twins absolutely cannot be beat in terms of a fun street car. Even an undersized pair of twins that make nearly instant boost will still outshine most similarly capable singles up top. I don't like lag so I always run twins. And I'm not talking logged boost VS wot, I'm talking about having driven countless amount of turbo cars and knowing the difference in feel when you roll on the gas of a single or a small set of similarly capable twins. Transient response is what you feel in normal every day driving and you get it in spades with a good twin setup.
Rear mount? Sure they can be fast at the strip as you have time to get the things online while you're bumping it in. As for a fun driving combination on the street? None that I've driven accomplish that. Wouldn't use it if it was given to me. (refer to, I don't like lag so I run twins/etc/etc)
Back to the cam thing. I'll use the cams we have available as examples because well, why not. I designed them and tuned them over the years so at least I can speak about them with experience.
TUO-216/216 114lsa. I would plan on bigger if I planned on over 700rwhp.
TU1-225/225 113lsa. I may consider a bigger cam if 950rwhp wasn't enough.
TU2-236/236 112.5lsa. If you have a combo capable of 1200rwhp and 7800rpm than this cam will work great.
Guess the point I'm trying to make on cams is that I think 90% of people cheap out on their turbo then over-cam the hell out of it thinking it will somehow compensate when in reality all you did was soften up the bottom end and midrange for no gains up top.
So, in closing, if you're building or planning a build on a turbo LS and your goal is to not be disappointed, THE most important thing to buy is a good turbocharger or turbochargers. Second is valvesprings. If you cheaped out on the turbo so you could buy more cubes, a different intake manifold, a different cam, a set of heads, a throttle body, an electric water pump, or even a torque converter, you've made a poor decision.
Rant over, let the flames begin
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Verdad Gallardo TECH Fanatic
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What I was referring to "What?" is your making boost going through an intersection at 1/3 throttle. I have twins and they are bad ***, but I either drive my car at 3k and then I can get boost at hint of throttle. I mean if you are going through an intersection, I assume you are referring from a stop you aren't but in the 1500 rpm range probably at most and hard to believe you are in boost. Maybe you are. I can romp on mine from a roll and light them up. However, if I am at a stop I am going to have to build some boost by footbraking to 3 grand first. Maybe yours is different. I did the twins strictly to do something different but there are plenty of single combo's that blow mine away and I think mine does pretty well.
As you can see in my pic my car leaves pretty damn hard and I cannot build any boost crossing an intersection. lol
As you can see in my pic my car leaves pretty damn hard and I cannot build any boost crossing an intersection. lol
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From: KS
Here is what I was looking for. It's not specific but it's accurate to me because my car during normal driving (more gas than needed but not exibition of acceleration) will find boost. My intercooler pump will turn on at 4#'s boost and run for 5 minutes after that happens. I'll be heading to a friends house pull up and kill the car. The intercooler pump is still running and I never went above 1/2 throttle or over 45 mph crossing town.
This is a bit hard to do as their are really a limitless amount of combinations you can put together. This is all mostly generalizations, not an exact parts list. Just thought it may be of some help to people as I've driven and tuned a ton of turbo cars so here I can share some insight as to what some of them are like.
First on the list is going to be what I think is the ultimate street/strip setup. The almighty Garrett/Tial GT35R in twin configuration. These things have amazing response. Even on a 346 and a manual trans you can practically be into boost before the clutch is fully engaged while pulling away from a stop light at 1/3 throttle. Cruising along in 2nd or 3rd and roll onto the gas as you watch 2 black tracks in your rear view. Along with all of this transient response awesomeness they are still capable of 1000 at the tires. I recommend using the Tial stainless v-band housing. Say, .63 a/r for 346ci and .82 for 400ci, 1.06 for 427. Not cheap but usually parts that are ******* awesome don't fall under the ultra-budget category.
First on the list is going to be what I think is the ultimate street/strip setup. The almighty Garrett/Tial GT35R in twin configuration. These things have amazing response. Even on a 346 and a manual trans you can practically be into boost before the clutch is fully engaged while pulling away from a stop light at 1/3 throttle. Cruising along in 2nd or 3rd and roll onto the gas as you watch 2 black tracks in your rear view. Along with all of this transient response awesomeness they are still capable of 1000 at the tires. I recommend using the Tial stainless v-band housing. Say, .63 a/r for 346ci and .82 for 400ci, 1.06 for 427. Not cheap but usually parts that are ******* awesome don't fall under the ultra-budget category.
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From: KS
What I was referring to "What?" is your making boost going through an intersection at 1/3 throttle. I have twins and they are bad ***, but I either drive my car at 3k and then I can get boost at hint of throttle. I mean if you are going through an intersection, I assume you are referring from a stop you aren't but in the 1500 rpm range probably at most and hard to believe you are in boost. Maybe you are. I can romp on mine from a roll and light them up. However, if I am at a stop I am going to have to build some boost by footbraking to 3 grand first. Maybe yours is different. I did the twins strictly to do something different but there are plenty of single combo's that blow mine away and I think mine does pretty well.
As you can see in my pic my car leaves pretty damn hard and I cannot build any boost crossing an intersection. lol
As you can see in my pic my car leaves pretty damn hard and I cannot build any boost crossing an intersection. lol
On a different subject I read all the problems you had with the Precision turbos. It's funny because I needed restrictors on mine and when I talked with T-netics they told me a -4 feed to each turbos was too much. And you have precision telling you that you don't have enough oil.
I went so far as to put a T in each oil supply line, with a pressure gauge, to my turbos to find out what restrictor size I would need. It was educational because what I found was the turbos were seeing more pressure than the oil pressure gauge in the car showed. T-netics said 20 to 55 psi was where they wanted me to be at. I was seeing 80+ at 5500 rpm but the motor was about 70. It took a few tries at sizes to get it right.Crazy your On3's are still hanging in there. Precision should hang their head in shame.
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From: KS
I'd really like to ask you about the compounds on your Cummins. I have spoke with Phil at Anarchy Diesel about them and what he can do in EFI live for me. But you are such a hater you would probably tell me I can't do compounds on MY Cummins only you can right?
FormerVendor
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From: WWW.SPEEDINC.COM
GT35R is 62mm compressor/ 68mm turbine and ball bearing. Even at the same compression ratio the difference in response between these two sets of turbo's isn't even comparable.
I didn't save any part throttle data logs from these combos but twin 35R's with the right exhaust a/r (depending on displacement) have almost no perceptible lag and easily make boost at part throttle.
Don't be a jackass. You know I'm not saying it's instant. It comes on fast and doesn't take hardly any ground to see it. You here to hate our do you have some twin experience to share? How does your single spool?
I'd really like to ask you about the compounds on your Cummins. I have spoke with Phil at Anarchy Diesel about them and what he can do in EFI live for me. But you are such a hater you would probably tell me I can't do compounds on MY Cummins only you can right?
I'd really like to ask you about the compounds on your Cummins. I have spoke with Phil at Anarchy Diesel about them and what he can do in EFI live for me. But you are such a hater you would probably tell me I can't do compounds on MY Cummins only you can right?
I have never changed engine combos or cam but have changed turbines vastly. Tc78/78gts/pt88/hp8811(111mm turbine)
I can tell you just like ITDMD8 says, matching that turbine to the compressor is huge for spool. You need enough turbine to drive the compressor
The gts spooled better for me than the baby 68mm turbine tc. That was instant boost even though the gts and tc shared the same compressor but the gts was a 75mm turbine
Just like comparing the pt88 to the current turbo. The pt88 turbine is a mismatch to the big compressor
I agree the beauty of the twins is that turbine capacity is easy to accomplish. But if you take a pair of twins and put it up against a single of similar turbine and compressor capacity there will not be a huge difference between them
The twins on the cummins are very small for towing. I can make 15 psi of boost in neutral at 3000 rpm lol
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From: KS
Sold my 12 valve this Summer and moved up to the common rail.
Is there a reason why there are more 8 second streets cars using a big single (88mm-94mm)turbo rather than using twins? Just wondering because over looking the forum, I see a lot more big single turbo f-bodys going 8's that are street cars, I've only seen a few twin turbo cars running that number, unless all the twin guys are not sharing there builds. Can someone help me out here?
FormerVendor
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A BIG part of how they respond is the size of the compressor wheel.
99% of people want the biggest comp wheel that they can buy for that turbo.
It takes energy to turn that larger wheel and if you are only going to use 75% or less of it's potential then your trading response for "bench racing stats".
Most could get by with the old tried and true 57 trim good for about 425 each or the 60-1 good for about 550 hp each.
But No, I gotta have turbos with the mathematical potential of 1500hp but most do good to make 650 hp to the tires for one reason or another.
99% of people want the biggest comp wheel that they can buy for that turbo.
It takes energy to turn that larger wheel and if you are only going to use 75% or less of it's potential then your trading response for "bench racing stats".
Most could get by with the old tried and true 57 trim good for about 425 each or the 60-1 good for about 550 hp each.
But No, I gotta have turbos with the mathematical potential of 1500hp but most do good to make 650 hp to the tires for one reason or another.
Last edited by Chris@CBR; Jan 13, 2014 at 08:38 PM.
