sr20dett

[orange_guy182]

Is is just me or does this look like this sr20 has twin turbos?http://store6.yimg.com/I/phase...24566

[Sintax]

nope, thats just you, that other deal back there provides cooling for the driver during long endurance runs. :pface

-scott

[orange_guy182]

So that "deal back there" runs off the intercooler? And why is it so far away from the firewall if it cools the driver?

[Boostn]

Haha... you've got to learn to take a joke man.

[Movingviolation240]

it dosn't look like twins, they ARE twins.....

[orange_guy182]

Also I think that engine has been bored out to 2.2L by the sing to the right that says sr22.

[BinaryVertigo]

okay what's up with this...people with stock twin turbo are doin single turbo conversion while others are doing twin turbo conversions? wtf? can any1 explain why the difference in preference? thanks

[Randman]

I wonder how much lag he gets, the exhaust housing on the further back turbo looks huge while the compressor looks fairly small, which I am sure must help with some of the lag, but still, it's only a 4 banger.

[Sintax]

i suppose if he were running the turbos sequentually there would not be much lag at all, if the turbos are of two different trims.

a lot of the reason the big supra boys are going from twin turbo to big single is because of cost. two turbos doubles the cost of everything, because on your turbo manifold you have twice the work, you have to run two times the cooling lines, two times the intercooler pipe, two times the TURBOS, and those of you pricing bigger turbos know how bad that gets, if one turbo was not expensive enuff....

there are some performance ends too

-scott

[Team503]

okay what's up with this...people with stock twin turbo are doin single turbo conversion while others are doing twin turbo conversions? wtf? can any1 explain why the difference in preference? thanks

I'm going to cover this from my RX-7 background (stock sequential twins).

There's singles, parallel twins, and sequential twins.

Single Turbo:Pro: Huge potential, no flow restrictions, simple plumbingCons: LAG - the bigger the turbo, the bigger the lag is a good rule

Parallel Twins (usually implemented on V6 or V8 applications):Pro: Faster spool than single (each exhaust bank spools on turbo, such as on the 300ZXTT) so more responsive, plumbing is still simpler than sequential twins, but doubly complex as the single (there's two, dork).Cons: Some restriction on ultimate flow potential due to receiving only 1/2 of exhaust flow, lag, but less than a single

Sequential Twins (implemented for driveability, only Supra and FD stock):Pro: Fastest spoolup, best driveability. Example is the FD: first turbo spools at 2,000 rpm, second at 4,500, so you're always in at least some boost. Very easy to drive around town and in traffic, no sudden bursts of power, powerband is VERY smooth.Cons: Extremely complicated plumbing (the FD utilizes over 120 vacuum hoses for sequential operation), lowest power potential (most restrictive setup), expensive.

Think of it this way. You're using exhaust gas to spin a turbo, right? And a turbo is basically two fans connected by a shaft, right?

So the more exhaust gas you throw at it, the faster it'll spool. But on the other hand, the bigger the fan, the more it takes to spool it. In a fictional world, let's say you get enough exhaust out of that SR20 to spool a T04 at 3000rpm. Take that T04 off, replace it with a T88, and it'll spool at 5500rpm, right?

Ok, so now we've established turbo sizes. What happens when we throw twins in the mix?

Well, you can make the same power as a big turbo using two midsize turbos, or the same power as a midsize turbo using two small turbos (say, instead of a TD04e, using a pair of T25s or T28s). Why? The actual flow displacement of the two smaller turbos is EQUAL to the flow displacement (measured in CFM) of the larger turbo.

How does it work?

Now it depends on the layout. There's two kinds; parallel, and sequential. They are, in fact, exactly what they sound like. With parallel twins, the turbos run SIDE BY SIDE, and with sequentials, they run IN A ROW.

The best text illustration I can come up with is {oh, ph33r my 373313 sk177z y0 } (Ex = Exhaust source, TU = Turbo, IM = Intake Manifold)

Parallel:

Ex -> Tu \___ IMEx -> Tu /

Sequentials:

Ex -> Tu -> Tu -> IM

So you can see the advantages of the sequentials right there; the first turbo receives the FULL exhaust flow to spool it faster, while the parallel turbos are getting half the flow each. And the first turbo assists the second in spooling in the sequential operation! The disadvantages? In a sequential operation, you can see that the first turbo would impede ultimate flow potential to the second (rather than having it's own path of exhaust, it has to share), and that the second turbo impedes the compressed air coming from the first. There are also the associate heat problems (adbiatic efficiency) associated with two compressor wheels churning the same air and heating it up. As we all know, hot air is less dense than cold air.

So ultimately, the best setup for a street or roadcourse driven car is either a very well matched single or parallel twins. Only a street only car will benefit from sequentials in the long run, assuming that ungodly amounts of power are the goal.

Hope this helps!

EDIT: Just saw that someone mentioned cost. For a good comparison, a single turbo kit for an FD runs around $4500 - 5000 with FMIC. An upgraded twin set costs $3400 for just turbos. A full kit would probably cost around $8,000+.

EDIT 2: Also, don't forget with twins that you're pushing alot through the same manifold, and the manifold often becomes the greatest restriction involved.

[Sintax]

haha very well put, he had the patience to say what i was thinking!

5 stars....gave diagrams and everything.

[Team503]

haha very well put, he had the patience to say what i was thinking!

5 stars....gave diagrams and everything.

Awww... Thanks!

BOOST RULES :ylsuper

[I H8 UR DSM]

Cowboys rule!

[Team503]

No, PUNK rules. :ylsuper

And honestly, I just don't have any good sig material.

[Nils]

I'm going to cover this from my RX-7 background (stock sequential twins).

There's singles, parallel twins, and sequential twins........... often becomes the greatest restriction involved.

Good post. I agree with you 99% =)

Twin sequentials do offer great spool but I would have to disagree with you that upgraded true paralell twin turbo set-ups spool sooner than a large single turbo. Remember, the exhaust housing on a single turbo might be large, but it has twice the amount of runners/exhaust gas pushing it ... where as a twin turbo kit uses less exhaust gas for each housing.

Turbo is turbo, single or twin... the bigger it(they) are the more lag you will get.

As you mentioned in your post, the pros for a single turbo outweighs the pros of a twin turbo kit. Twin turbo kits look cool and if I was building a show car that might be something I would consider, but, for bang of the buck and pure performance a single turbo is a better choice =)

take care,nils

[I H8 UR DSM]

nils, let us in on your S14 project : )

[fastim87]

Alright, you guys will probably laugh at me for asking this question, but thats how it goes. If your turbo spools at say 3000rpm, then couldn't you just launch at that or higher and have it already spooled for your race?

[Nils]

nils, let us in on your S14 project : )

ahhhh.... the 240 project has been a nightmare. I have been sorting out fitting the rims on the car and it has been a nightmare. Got H&R wheel spacers with extended wheel studs, but the H&R wheel studs were not long enough... arrgghhh!! So I had to order $100 Nismo 60mm wheels studs, they worked fine. then I had to get 5mm spacers for the rear. On top of that I have ripped out the wiring harness in the left front fender twice while road racing... fried wires going all the way to the ground connection by the radiator, nightmare to sort out and fix but it is all taken care of now and I tap screwed a piece of aluminum to protect the wiring harness from anymore tire rub. I have also been testing some brake pads to see which work best with the 300z brake swap. So far the Carbotech XP pads have treated me the best at the track. Porterfield R4 pads are very good aswell.

At this point I have not aquired the funds for the sr20det swap but it will happen soon. Once the funds are there I will transform the 240 into a worthy road racing car and I will make a site comparable to to4r.com about the 240 and the racing I will be involved with.

thx for the curiousity =)

take care,nils

[Nils]

Alright, you guys will probably laugh at me for asking this question, but thats how it goes. If your turbo spools at say 3000rpm, then couldn't you just launch at that or higher and have it already spooled for your race?

Dont worry, No laughing matter.

yes you can... but you loose valuable powerband. For drag racing spool is not as big of a concern as road racing since you can build boost at the tree and keep that boost through out the 1/4 mile.

take care,nils

[I H8 UR DSM]

ahhhh.... the 240 project has been a nightmare. I have been sorting out fitting the rims on the car and it has been a nightmare. Got H&R wheel spacers with extended wheel studs, but the H&R wheel studs were not long enough... arrgghhh!! So I had to order $100 Nismo 60mm wheels studs, they worked fine. then I had to get 5mm spacers for the rear. On top of that I have ripped out the wiring harness in the left front fender twice while road racing... fried wires going all the way to the ground connection by the radiator, nightmare to sort out and fix but it is all taken care of now and I tap screwed a piece of aluminum to protect the wiring harness from anymore tire rub. I have also been testing some brake pads to see which work best with the 300z brake swap. So far the Carbotech XP pads have treated me the best at the track. Porterfield R4 pads are very good aswell.

At this point I have not aquired the funds for the sr20det swap but it will happen soon. Once the funds are there I will transform the 240 into a worthy road racing car and I will make a site comparable to to4r.com about the 240 and the racing I will be involved with.

thx for the curiousity =)

take care,nils

so what rim width you running? with what offset? (im a s13 guy, so i dont care that much, hehe)...i know you had like 275's on the rear last time i saw a pic...nice and meaty!

good lucktime, money, time, money, time, money...etc etc etc : )lifes a *****....then ya spend more money : )

[Nils]

so what rim width you running? with what offset? (im a s13 guy, so i dont care that much, hehe)...i know you had like 275's on the rear last time i saw a pic...nice and meaty!

good lucktime, money, time, money, time, money...etc etc etc : )lifes a *****....then ya spend more money : )

17x8 infront and 17x10 in the rear =)

cant remember the offset, too long ago.

take care,nils

[Team503]

Alright, you guys will probably laugh at me for asking this question, but thats how it goes. If your turbo spools at say 3000rpm, then couldn't you just launch at that or higher and have it already spooled for your race?

For drag racing, one word. WHEELSPIN. Slicks are a whole nother matter though.

And Nils is right, you lose valuable powerband.

Nils,

Regarding the twins vs. singles, you have some good points. I'm a big fan of parallel twins in the right application, especially road racing, where responsiveness is more important than top end power (especially when the rules often restrict that power anyway).

I think large singles pretty much only work well for drag racing - the shape of the powerband isn't exactly "turn-friendly", and trailbraking will only get you so far.

In the application this board centers around, coming from a smallER displacement background (that 1.3li rotary only phsyically displaces .65li), I would stay on either midsize parallel twins or a slightly sized single.

Considering the cost of correctly engineering the manifold for the proper flow characteristics, I would say simply that a well designed single turbo implementation would be wisest.

On that note, does anyone have any measurements of the flow output of the SR20DET, from idle to red? I need to know how much EG is getting pushed out to size the turbo right. And corresponding temperature readings wouldn't hurt.

[Nils]

For drag racing, one word. WHEELSPIN. Slicks are a whole nother matter though.

And Nils is right, you lose valuable powerband.

Nils,

Regarding the twins vs. singles.......... temperature readings wouldn't hurt.

Agreed =)

take care,nils