so its been a year and a half now since ive been involved in the car game...the car is looking great and I am really getting a good idea of how everything is going to come together. Now this coming season, I was looking to step it up a bit. I was going to go all natural aspirated and build the shit out of the motor, but i figured I'd beat it up a bit and maybe try some custom turbo or twin turbo is thats even possible. I just want peoples opinions. I have tons of creative honda enthusiast friends, and i just learned to weld so I am looking to explore. I live in a rich are filled with exotic cars and they do give me respect, but until they are all seeing my tail lights im not happy. IS IT A MYTH THAT IT IS UNHEALTHY TO TURBO AN AUTOMATIC?

 

Damn, your car looks good.

 

Anything is possible. I know of a few cases where the J series has been Twin turboed but its not a common occurrence. You would be better off build a single turbo setup. With the turbo game being relatively new for the J series and the TL, I would stick with that, Im sure 450whp out of a single turbo kit will be fun once the cars built.

 

a single turbo will do fine!

torque at 2500 RPM!


there are limits to the auto tranny.
you'll need to figure out a goal for you and your car.
once you find a goal in mind, whether it be 340hp - 500hp, is up to you and how much you want to spend to beef up shit.

we've found that the TL responds nicely to about 380-400hp. that magic number 400 and up is where things start to get crazy

 

The 5AT seems to lack a good set of aftermarket clutches to hold the power. The one person here who no longer has the ride swapped the 5AT to a 6MT after building the engine and producing mid-high 500's.

Even with the 6MT, that same ride ate through 4th gear and another J35 or J37 stroker putting down equivalent numbers ate through 4th almost instantly because of the torque difference.

Being FWD, it's also a beast to drive at those levels.

There is a solution from M-Factory for straight cut 4th gear set, there has only been one set cut and people are trying to recoup the tooling cost. Last I heard it was a $1200 bill. You may be able to contact M-Factory and get another set run but the minimum is 10 sets at something like $8K when I inquired a couple years ago.

You'll may hear from IHC who I believe will tell you that a twin setup isn't needed. Our 62mm turbos are capable of producing enough boost to get you into the insane HP range and the fact that there is very little room under the hood would push the snails out back somewhere.

 

Thank you guys! I will be noticed on the site soon for sure

 

this guy has a twin turbo accord.

http://www.v6performance.net/forums/...ell-whole.html

 

A twin-turbo J is a little comical, especially in a FWD car. A single turbo will be plenty good enough for you! I too have a 5AT TL and am thinking about doing a turbo conversion, according to our mechanics here at Acura the transmission in the Type-S is the strongest AT to come out of Acura in a LONG time and too this day have seen very, very few failures.

 

The Type-S AT transmission is actually quite beefy but it also has several weaknesses. I've had a turbo kit on my car for over a year now and for the most part the AT transmission has been able to handle the power. However during wot the gears will get stuck sometimes.

 

this doesnt really tell us anything at all.
please continue to contribute by expounding on some of the pertinent information, like....
who built the turbo...?
how much hp are you running?

as stated lilbert has found the limit to the automatic tranny, as he busted it and then swapped it for a 6MT which still got torn up by 500hp...

 

I'm surprised by the number of helpful posts in here.

 

I'm pretty sure bert was north of 500.

 

Let's get the myths out of the way first. Two turbos do not make more hp than a single similarly sized turbo. The choice to go single vs twins is usually a packaging requirement. Sometimes a pair of small turbos will fit in places a large single won't fit.

Power delivery can be a bit different. A larger single will usually spool quicker. It gives that on/off feeling which I love for drag racing. Twins are usually a bit more subtle and linear. There are exceptions to the rule though.

Our autos generally don't break, the clutches slip first.

As for the details they can be found in the hundreds of pages in the turbo thread.

 

The number of turbos isn't about power

edit: what IHC said.

 

I'm in total agreement with the fact that the 5AT is the stronger of the two transmissions offered in the 07-08 TL-S. It was purpose built with much larger shafts and clutches than the previous AT5 not to mention much stronger. The hydraulics and electronics are a much more dependable/reliable design and I run the transmission on my turbo Accord with a j35a8 (as high as 15psi)...soon to be an up and running 3.7 liter. I was told by many how it wouldn't sustain and would eventually fail (which it will) bringing disappointment. BUT, I'm still running it and its still going strong. Two things...well three: run a high quality, synthetic ATF, replace the fluid in half the time that you would normally wait, and most importantly don't allow the transmission to shift when WOT and power applied. Those are the three basic principles I follow and have passed on.

Truth is, automatics are much more widely used in racing than manuals for reasons of being better performers. As for traction issues, I haven't had one incident that I can recall where I lost a race or was disappointed because I couldn't gain foot. Then again I do run wider tires.

Good luck and run a single...you'll thank us and yourself later.

 

Sorry about the “unhelpful” post earlier I was short on time. It’s been a little over a year now since I had the J&R turbo kit installed on my 07 Type-S AT and I have been quite impressed with the results. So far I have had several tunes ranging from about 310-370 hp with similar torque and have had no issues except with the transmission. Even in the low 300 hp range the transmission would slip sometimes between 2nd and 3rd gear. In my experience this usually only happens after a few back to back wide open throttle runs. 90% of the time I have no issues with the transmission and the car runs great.

It is definitely a myth that it is unhealthy to turbo an automatic. People just prefer to go manual because the stock transmission can handle more power. If your goal is to just make the rich people in your neighborhood see your tail lights a single turbo AT should be able to accomplish this. However I wouldn’t recommend tuning over 350 hp unless you plan on beefing up the transmission.

 

Turbos and autos are a natural match. The auto is going to be quicker every time. You have a continuous flow of power and no lifting and respooling between gears not to mention you can powerbrake and build boost off the line with an auto.

Now for those thnking FWD is not much of a disadvantage in a high hp application I strongly disagree. There's no fwd car that I won't put 5 cars on in the first couple seconds. Any serious RWD car will leave a fwd car like it's standing still and it will be hurting for traction at a higher speed than RWD.

 

libert didn't bust it, it just started to slip on 4th gear, super long pulls.

It would have been very interesting to see if libert did a fluid change to something else, or tried to adjust the line pressure a little and see if it solved the problem.

 

Sounds like you need a automatic trans cooler. After a couple of pulls the transmission fluid is heating up, which makes it thinner, which makes the fluid pressure go down, which makes the pressure on the clutches less, which makes the tranny then slip.

It would be interesting for you to just ghetto rig a transmission temp gauge up and tap it to your window and do a couple pulls and watch what your transmission fluid temp does.

 

when Rodney was still legit, he told me that the 5AT will hold 360-400hp without an issue and after that as mentioned here clutch starts slipping and the gears go down the drain....

plus for a twin turbo, you have to realize that you are on a FWD platform....my car is barely putting down 260whp and weights 2950lbs, and I spin 2nd on summer tires....you looking at 400hp and even if you are full weight at 3700 lbs, you will be spinning 3rd and prolly even 4th....

I think the sweet spot for the TL is 325-350whp...try to be in that spot and put down all the power you are making, that will be more fun IMO

 

 

...

 

 

I understand that on good tire the TL might put down 325hp from a slight roll,'rolling into it. Here's what I'm talking about though. I can take the TL and GN and launch both on a cheap street tire and the GN won't take it by much. Put them both on tire and the TL if it has the power will take off decently hard but it's going to spin. The GN is literally going to have 10 cars on it before the TL can make the shift to second gear. One will jerk your head back a bit, the other makes your head spin, the skin on your face noticeably stretch backwards, and a sense of violence.

Imagine for a second being able to set one of the 500+hp turbo TLs on a 5,500rpm 2 step limiter and sidestep the clutch with the throttle to the floor and put all of the power to the ground with no wheel spin. It's something most including myself did not realize a car was capable of such violence until I experienced it the first time. This is why I look at a high power TL as fun but not a serious competitor against a serious car in a drag race.

One thing that has to be noted is a 5at turbo TL must be run on Type F synthetic fluid, no mixes, and preferably Redline racing since it's thicker and will help retain shift quality. The type f makes a tremendous difference in clutch holding power. The auto should be capable of better launches with the turbo and quicker all the way down the 1/4 assuming you don't push through the converter.

 

 

THATS WHAT IM SAYIN! but i feel like twin turbo would be a more efficient setup for better air flow. so two smaller turbos doesnt sound bad...maybe with a true dual magnaflow exhaust. all i know is that for now i will be preparing my engine for turbo, then when i feel the time is right, i will make the move. but most likely twin turbo.

 

I ran my 5AT on a j35a8 @ 15lbs with ZERO issues.


I mentioned above my three fundamental rules of what allowed this. I do also run a ATF cooler and almost always drive in sport shift mode even in regular driving situations.


Id say the next big thing for someone to do is modify the 4g TL-AWD auto for FWD only use. These transmissions have been beefed up with larger diameter shafts (15% larger to be exact), stronger casing, better performing clutches, increased line pressure control for faster shifts and even an improved (stronger) lockup torque converter.


Most of those same improvements were made to the AWD's 6MT as well except shorter gear ratios between first and fourth gears. Also increased clutch pressure without increasing the effort from clutch pedal actuation.


Yum yum....

 

 

Twins are not more efficient. Efficient meaning charge air temp, back pressure, transient response, etc. You have double the rotating parts that even though are smaller they equal more weight to spool up which hurts transient response.

There are singles that provide over 2,000CFM and support over. 1,600hp. If you take a single with 400CFM flow and twins with a combined 400CFM flow you're going to make very close to the same power with the main differences being power delivery. Do you want it linear but a little later or do you want it all at once and a little sooner.

As I said, there are exceptions to every rule. A twin hung straight off of each head may spool quicker than a single that has 10' of exhaust piping and associated volume between the heads and turbo.

Let's not forget regulating two turbos vs one. Both turbos have to be delivering the same psi for maximum performance. Most are set up to sum once they enter the intercooler (two in, one out) but if the goal is 10psi manifold pressure a d one turbo is making 12psi while one is making 8psi you're heating up the charge air unnecessarily and driving up back pressure. You need two wastegates and double the inlet tract plumbing.

 

I'm just going to leave this here....it's a good start for a mods list LOL

 

Don't know why they into minivans...

 

WOW IHC your never wrong, but you blew it. A twin turbo will have more midrange because of better response when compared to a equal lb per min flowing turbo. So lets take two GTX28rs turbo's. Rated at 43lbs of air each they can make a total of 86lbs of air, or 860 whp roughly. On an acura NSX this has been done and shown to have better mid-range. Why. because the turbo equivalent would be a GT42/94R rated at 85lbs of air.

Also a guy named tony the tiger went from a single Kai51R turbo on his 3.0 liter camary to a twin turbo set-up. He made an equal like 600 whp, but said the twins had WAY MORE MID-RANGE power. In the end he went back to the single turbo set-up saying it was just more fun to drive since the boost was on or off, unlike the twins which were way more linear in there delivery with there faster response.

When talking to a garrett engineer he said that what you don't realize is that when you jump to the larger frame size turbo's not only does the wheel size increase, but also the shaft size. The shaft size adds WAY more weight than you think but it must be done since the torque on a single wheel is so much greater. Because of this Garrett themselves said twins of equal size will spool faster than a single. Also the twins usually offer better, and shorter flow paths. Also can offer less firing order interference and turbulence before the exhaust wheel.

If you want a faster spool better midrange set up, Twins everytime. If you want a easier/cheaper set-up. Single.

 

Nope. The only way that can possibly be true is if your turbos are badly undersized to the point they're maxed out and can not flow more air. No one sizes turbos to be maxed out under full throttle at redline much less at full throttle and mid rpms. They're usually somewhere between good spool vs compressor surge. Too small and you're blowing a bunch of hot air and making no additional power.

Big turbos will have larger shafts but each turbo does not have it's own dedicated size of shaft. The same diameter is used over a large range of turbo sizes. I typically ran a stock GN sized shaft up to a TA62 turbo back in the day which supported 600whp. The TA64 was the first step up to a "big shaft" turbo at the time. So every upgrade from a TE44, TA49, 61, 62, et had the same sized shaft. While the shaft adds weight, it's still very small in diameter so it's not like you're adding weight around a 3" circumference. Let's not forget you're trading one larger shaft for a pair of smaller shafts with twins.

This "better response" you're speaking of is fictional. If a turbo can hit full boost by 2,000rpm, how will it have better mid-range response at say 3,500rpm if it's already fully spooled? Manifold pressure is regulated to be a constant from the lowest rpm the turbo can make full boost to redline. Once it's at full boost it's at full boost. Assuming charge temps and exhaust backpressure are the same, hp is going to be the same.

I mentioned the advantages of twins already such as the shorter flow paths you mentioned. However, you're making these huge blanket statements that can only hold true in rare circumstances that we are not likely to encounter in a properly designed turbo setup. To say if you want faster spool and better midrange you must use twins is an asinine statement. I don't have to rely on others, I've done it with some of the best in the world.

What you need to take away from this is peoples subjective feelings vs what's actually going on. A large single is going to come on hard and slam you in the back. A pair of twins is going to take just a hair longer to build power and this might feel like more midrange since you didn't get that kick in the ass down low from the larger single.

So again, twin vs single usually comes down to a packaging requirement by the manufacturer. The newer GT series turbos really changed the game to the point it doesn't matter much like it used to, turbos spool so quick these days lag is almost a thing of the past.

I hope you see how your argument collapsed in on itself. I'm sure this Garrett engineer knows his stuff but you may not have interpreted his explanation correctly or in the right context. It would probably help if you define what you mean by "midrange response".

 

 

Nope. Crap. I don't want to write a lot I just want to set the record straight. I'm trying to do this in as little words as possible here goes.

1. Every dyno out there on a engine that has had a twin turbo and single turbo set-up of equal power says your wrong. Data is data you know.

2. You telling me you had the same shaft size on all of those turbos is great but I would assume you were only increasing flow by just a few lbs per min. When increasing flow by 10lbs more a min garrett talks about how shaft diameter must be increased because of the increase in loading on the shaft which would cause it to bend if it wasn't increased. You listed no flows just said you went with bigger wheels so I don't know how to respond. Also as the wheel gets larger they increase diameter of and size of fins since the fins are longer they apply more torque on the wheel fins themselves as the lever arm is great. They talk about how wheel weight isn't directly proportional to size but instead is more like 1.5x size.

3. Usually small twin turbo set-up like the GTX28/rs turbo's I listed above will make max efficiency at a lower P.R. than the big singles who shift there compressor maps up and right for more efficiency at higher P.R.'s.....meaning their shaft speed has to be WAY higher to reach said power. meaning more spool time. In the example of the Camary he ran 19 pounds on the twins while on the single he ran 30. Before you say this is an un-fair since equal boost should be run look at the compressor maps. Small turbo's DIE over P.R.'s of around 2.0-2.5, while big boys don't start to push good amounts of air to keep up with twin till over P.R.'s of 3.0+. The goal was equal power. The single made 600 wheel and twins made 600 wheel. Twins did it at 19 psi and spooled faster....so more mid-range. One thing to note was while both made the same peak HP, the small twins started to choke flow uptop and the twin made peak power and started to die long before redline, while the single made the power closer to redline. Very different power curves for sure.

I like your responses IHC. I was actually in your shoes probably about 4 years ago. I had to go and read data, talk to engineers, and finally pulled some compressor wheels and measured them before I got convinced. I thought it impossible that two turbos rotating mass could be less than one, but then again how could I dispute all the factual evidence I found when I looked at twin turbo set-ups that went to singles. And why did BMW first go with a twin set-up only to later go to a single after having better packaging, but editors wrote that the car lost, "thottle response". Really I could go all day but if your mind is made up no amount of evidence will convince you.

NOW. I must apologize if this reads like crap with tons of typo's. I don't have time to go back and read it. sorry.

 

 

Yes, let's set the record straight. Let's start by clarifying what I originally said about single vs twin turbos. We'll start with this quote from my previous post before you stepped in. "As I said, there are exceptions to every rule. A twin hung straight off of each head may spool quicker than a single that has 10' of exhaust piping and associated volume between the heads and turbo." Said another way, exhaust enthalpy is the biggest thing a twin setup has going for it but even then the twin setup doesn't always have the advantage.

Let's define spoolup as well. There's boost threshold which is the rpm at which the turbo is first capable of producing boost. There's transient response or boost response which is how quickly the turbo will hit full boost once you put your foot to the floor. Some twin setups are capable of a lower boost threshold but the single is the usual winner in the transient state. Again, you're forcing me to make blanket statements due to your blanket statements.
Show me every dyno. I've done the dyno work first hand through the years. Trying to keep every variable the same and also trying to optimize each setup the single usually came out on top for my needs.
Yes, turbine and compressor wheel weight are not directly proportional to diameter but you gain a ton of surface area for a relatively small increase in diameter which levels the playing field and translates into better flow, less backpressure, and more torque applied from the turbine for a relatively small increase in size. It's like anything. Let's take a subwoofer. A 15" sub has about the same surface area as 3- 10" subs, not 1.5 10" subs. So saying weight increases 1.5x for an increase in diameter is leaving a whole lot of info out to try and win an argument.

The turbos I mentioned ranged from 340cfm to 700+cfm all on the same shaft. CFM will suffice for comparison's sake. Each size up turbo does not get a larger shaft, many different size turbos share the same shaft diameter. That longer lever arm or the turbine and compressor wheels will create more torque on the shaft but it does not have to spin as fast for a given flow rate.

I found this from Garrett -A pair of GT2860RS turbos will have a very close total MOI when compared to a comparably sized single turbo (GT4094R). Now where is this supposed quicker spoolup coming from with the same MOI? A twin scroll design all but eliminates any scavenging/exhaust pulse problems. The larger turbo is naturally more efficient at compressing air resulting in lower charge temps and a denser charge air at the same boost level. So even though a single will spool just as fast and faster in some cases, it's going to be making more power per lb of boost which is more important than the boost (restriction) level itself. In addition to having the same MOI, the larger single will usually require fewer rpms to flow the same mass of air and you can probably see how this can result in a turbo that's quicker to hit full boost.

I did not think I had to bring it up but maybe I do. Each single gets half the exhaust volume/flow/energy/enthalpy. As I cited before you came in, the one advantage singles have is the potential to be mounted closer to the heads and that's a big enough difference to give them the advantage in spool over a large equivalent single but again, at high boost/high hp the single is still going to shine.
There's nothing to be said here. I don't know the AR of either turbo, the flow, hell, anything about either setup. You have a set of twins at 19psi and a single at 30psi. They could be any size, any AR, I don't know the exhaust configuration, nothing pertinent for a rebuttal. From what I'm reading I would say the singles were undersized resulting in better spool but a loss of top end hp and the single was oversized resulting in the opposite.
No one has disputed the a small turbo has a lower rotating mass than a large one. When combined, the moment of inertia is close. Each single gets half the exhaust flow. What's so hard to understand? I would like to see measured boost threshold and transient response from twin to single, not peoples feelings about which one spools better.
What evidence? You read about it, good for you for educating yourself but I've been out there doing the testing. BMW like most manufacturers manipulates boost and throttle response electronically. My friend got his N54 "chipped" and the boost came in sooner and more abruptly. My friend's CL600 Mercedes when put in dyno mode has much quicker spoolup. The turbos are not changing on these cars, just the engine management which has a HUGE influence in spoolup. I found a way in the '90s when spoolup was a huge problem to pull ignition timing waaaay back just during spool and I went from having to use nitrous to spool it up decently to almost instant boost with no nitrous. There are many reasons why the single turbo Bimmer lost a little throttle response from engine management to more restrictive exhaust after the turbos to a hundred other variables that are unrelated to single vs twin.

What you've done is take little bits and pieces of conversations and articles and put them together to fit your belief. You might have been better off 4 years ago.
Since Google is the god of all knowledge, here's an excerpt from Garrett themselves (and I HATE Googling info): "In most cases, for top performance, a single turbo is preferable because larger turbos are generally more efficient than smaller turbos. However, often there is not room for one large single, or the tuner wants the visual impact of twin turbos. The notion that two smaller turbos will build boost faster than one large turbo is not always accurate because even though the turbos are smaller, each one is only getting half of the exhaust flow."

You have a lot of knowledge, it's actually nice debating with you but it's how you put it together. In the real world we have people dialing boost back, creating artificial lag from both twin turbo setups and single setups because they build boost so quickly the engine internals become questionable due to rod journal loading at low rpm.

Don't worry about the spelling, I rarely put more than a few minutes into these things and never proof read myself. I'm usually horrified when go back and read them days or weeks later.

 

Instigator.

 

Twin= top end power
Single = faster repsonse

/ end..

 

Exact opposite.