maat's idea reborn (sequential turbo)

[95kate]

ok guys i'm new at this and i prolly sound dumb but i really wanna find a way for this to work. i got a 95 GS-t with a imported japanese EVO III engine swap and a Garrett T-4 turbo upgrade. i only could find one thread on this by maat and it didnt really help so i'm starting a new one.
this is off in the distance but i'm trying to get my plans together so i can do this right the first time.
ok here goes.... ok my old turbo i busted at the track (w00t) gave me i think around 7-9 psi and boost pretty much started at 2800 rpm. my T-4 starts kickin in at 4500 rpm. most people might have gone with a T-3/T-4 hybrid. yeah i know, but i'm that one person that's always different. basically my theory was similiar to maats but a lot simplier. i'm not really trying to get rid of lag altogether, i'm trying to replace the T-4 lag with boost from the T-3 or TD04 or whatever. i thought of having a large wastegate set at a low psi for the small turbo to prevent the turbo from spinnin too fast and cut down on a lil of the lag having a "reverse wastegate" (a wastegate that closes with more pressure insted of opening) set after the exhaust outlet. the exhaust would go into the small turbo like normal but with the wastegate leading into the second turbo insted of the downpipe. and once a certain psi had been reached all the exhaust going out the downpipe would be shut off by the "reverse wastegate" and rerouted into the large turbo. providing the second turbo's boost. just my idea i've been thinkin about for the last year. tell me what you think. i'm not too concerned about the large turbo's lag because that should be fixed bt adjusting the strength of the springs in the wastegates. and puls the large turbo would already be spinning by the time the first turbo topped out. i speculate that there would be an enoromus amount of lag in the small turbo at first though. i know it isnt feesable or practical but if this isnt good gimmie some ideas so i can make this work

Chris

 

[leet]

Where do you intend to fit another turbo under the hood of a DSM?

 

[peregrine]

use nitrous to spool that pig.

 

[ChicagoGSX]

If you could ever fit a T4 and another turbo under the hood you would never be able to engineer a sequential system, not to mention the problems of running two different sized turbos.

 

[Defiant]

It's absolutely the bestest, greatest idea EVAR!

You get to work on that, and take lots of pictures. The monkeys are keen on a formation flight. And their hangar is such a dank place.

 

[98spydert]

Suffer the wrath of the monkeys!


You think that T4 spools slow now... wait until you've got all that extra crap on there to reroute the exhaust here and there. My guess is you'd be lucky to even spool the T25


Good luck though

 

[Maglin]

Sequental turbos just don't work all that great. They are complicated messes. I would go with the spray to spool that pig.

 

[95kate]

Where do you intend to fit another turbo under the hood of a DSM?

yeah yeah i already heard all the "dont try to do it" , "it's too complicated" stories. i am determined to make monkies fly. and i'll keep throwing them off a building until i find one that will fly.

seriously, though, mounting although a problem isnt a large one. i had everything fabricated so this could be done later. nothing is going to be taken out (a/c, power steering or anything) the T25 (more than likely the one i'm going with) will be mounted with fabricated plates to the manifold. a spot on the passenger side of the manifold will be shaved flat and holes drilled for an external wastegate for the small turbo. the large turbo will be mounted 3" below the small turbo. unfortunately, i cant mount it straight because of the mount right smack in the way. so i have to shift the second turbo to the left (driver's side) and have the downpipe cut 2 " and bent 2" over. lastly my dipstick had to be pushed toward the radiator as far as possible. these are just the plans i have so far and i wont start on it until after i rebuild my engine (lower compression pistons, thermal treat the head, etc)

and the lag on my T04b isnt very strong, it just lasts forever. my car takes off like a N/T until about 4700-4800 rpm then it kicks in.

 

[Mirage2LTurbo]

What are the specs on your turbo?? I'm running a full t4 pt67 P trim and hitting 15lbs by 4700 with an exhaust leak. Maybe you should consider that there are other factors involved in why your turbo is so laggy....

 

[xxrealmsxx]

Everyone wants to twin turbo, for all that hassle make a supercharger or something. Twin turbo will never be worth it on a DSM, it's the equivalent of that tri-turbo supra, sure you did it, it's slow for the $ you paid but it sure is original.

I dont think it's worth it, anything is possible, but not everything is worthwhile.

 

[LaserDad91]

I thought this was the site where we are suppose to push our cars to the max? Maybe a crazy idea, but go for it and have fun!!

 

[Maglin]

Here are my thoughts on it. To make it work I think you would have to shut off exhaust to the second turbo once the big turbo reaches full spool. Probably have to do it with an electronic selonoid. (I can't spell it) Also once you cut the exhaust off you will also have to cut the CH off so you don't loose boost through it. Why I says you will have to cut off its exhaust is because you will need all the force you can get to spool your bigger turbo up. I've just worked on a sequential twin 3rd gen RX-7 and let me tell you what. It's a mess. We did the non-sequential conversion and it has more lag but it's so much easier to trouble shoot and we got rid of about 20-30 vaccumme lines. The way mazda does it is it shuts off the CH housing and Exhaust to the back turbo to get the front turbo to spool very quickly. A turbo pre-control opens at around 8 psi to start the back turbo spooling and once 10 psi is reached on the front turbo the back turbo control opens up and lets the exhaust come in and start it going. At the same time the butterfly closing the compressor outlet opens allowing the turbo to produce boost. This actually drops the boost from 10 psi to 8 and then it reaches 10 psi again and that is the stock setting for the RX-7. So it's boost is non linier and is 10-8-10 psi. With this sequential setup you also can't effectivly use a boost controller to control the turbo's becasue you are only able to control the front turbo as it's the only turbo that has a waste gate on it. The back turbo's boost is controled by the opening and closing of the turbo control basicly stoping and allowing exhaust flow through the turbo.

So it's pretty compliacted on the Mazda. For what you want to do you will have to make a lot of provisions to block the boost for both turbo's so you don't loose the boost from either turbo. And the 2.0 doesn't put out enough exhaust to have both turbo's fully going. And if you end up pusihing the smaller turbo to far it's going to heat up the intake charge which isn't a good thing, so thus you would just want to shut it off entirely once your big turbo reaches full spool.

That is why Nitrous is just easier plus it has the added benifit of adding a denser colder air charge and more O2. Not to mention you can safely add like a 75 shot of NOS get your turbo spooling faster for a lot less money and time. If you go for this more power to ya and take a lot of photo's. If anyone thinks or knows that any of my info is wrong let me know. I have the Mazda FSM here with me and I've read the Sequential Turbo set-up about 40-50 times so it's engraved into memory.

 

[shootr350]

It's absolutely the bestest, greatest idea EVAR!

You get to work on that, and take lots of pictures. The monkeys are keen on a formation flight. And their hangar is such a dank place.

Stop it my sides are killing me :laugh:

 

[leet]

yeah yeah i already heard all the "dont try to do it" , "it's too complicated" stories. i am determined to make monkies fly. and i'll keep throwing them off a building until i find one that will fly.

Fine. My question now is 'what are you going to remove so that you may fit another turbo in'?

I'm not trying to kill your idea, it is just basically impossible to fit another turbo.

 

[Gigaah]

Fine. My question now is 'what are you going to remove so that you may fit another turbo in'?

I'm not trying to kill your idea, it is just basically impossible to fit another turbo.

THis may or may not be a good idea..but on the scale of engineering feats..this surley doesn't rank high..complicated..oh yeah.. impossible...not by a long shot.

 

[Defiant]

impossible...not by a long shot.

Hm. Show us the other one that's been done in the 15 years there's been a chance to.

 

[Gigaah]

IMO people say things are impossible way to often. saying you cant get something like that to fit is impossible is a bit over stated. The enginuity of man far surpases a task like this. Now is it anywhere near worth it..the cost, time, effort, beneficial results? Well then the fact it hasn't been done or with any results DOES reflect upon that quite highly. You over look the fact the doing something that hasn't been done in and of its self often times
is more than enough to make up for anything else..and you know once in awhile when someone does that they hit on something that is great..then everyone starts doing it or learns they were wrong. Don't even get wrong..I'm not speaking of this project directly and I'm not saying I personally believe this is one of those..wich I really don't honestly.

Impossible? NO
Impracticle? Perhaps
Should he do it? Go for it man! Its better to have tried and failed..than to have never tried at all.

 

[leet]

Its better to have tried and failed..than to have never tried at all.

What, are you made of money?

Defiant merely proved my point.

 

[xxrealmsxx]

We all know it isn't impossible, but it's just like a rwd 2g, sure buschr's got one but no one else does. If someone is in the league of people (not trying to offend the poster) that would just up and do something of this magnitude they wouldnt come on dsmtuners asking or posting info about it. Most of us on here know our cars, but a twin turbo dsm as a viable option just doesnt make sense to 98% of us. The other 2% will say it's possible and egg other people on to do it, but in the years that these boards have been up so many have asked for info and none have done it. Original poster asked what we thought, and we let him know.

 

[ChicagoGSX]

The idea is just absolutely ridiculous. The list of problems is so long I guarantee you will never even come close to doing it. If you pull it off, I will personally paypal you 1000 dollars. You never answered my first question, which is how do you plan on running two turbos that are sized so different. Once the larger turbo spools it will push the air of the second turbo back and cause it to surge. Now if you run two similar sized turbos it would be possible to run them sequentially, but even then I doubt you will make it work. There is a reason there isn't a single car that has an aftermarket sequential setup, it is an engineering nightmare. Even cars that COME with sequential setups ditch them for single turbos.

 

[GPTourer]

I don't think Bushur's RWD Eclipse belongs in this discussion. His car is backhalved and almost completely re-engineered.

This guy wants to do it on a street car. Whenever this idea comes up, the results are always the same. The person that wants to do it has all these grand ideas, then all the naysayers say nay. Why bother asking for advice? Just do it and show us all a journal of pics and how to descriptions. Or keep it all a secret and just show the final pic of the engine bay and a video of the car tearing someone a new a$$hole at the track or on the highway. Just bring it. Personally, I just want to hear and see more about the current T4 setup you have now.

 

[FireyIce01]

okay, well, here's my thoughts on how I would do it... the first turbo would be the smaller one, it would be plumbed into the exhaust like normal, except, instead of the O2 housing, wastegate, and downpipe, put the wastegate on the manifold before the turbo, after the 4 passages have merged, and run a pipe from the exit of the first turbo's turbine into the inlet on the second turbo, and then put the downpipe and O2 and whathaveya on the second turbo, now put a cone filter right on the first turbo, and the outlet of the first turbo's compressor, into a *SMALL* intercooler and then onto the inlet of the second turbo compressor... this way, the full exhaust would be traveling through both turbo's, and the air being pushed through the second turbo will help to spool it... I think this would work because once the second turbo starts to spool, it will be creating a low pressure area between the turbo's which will make the efficiency of the first turbo appear to be higher, as it will no longer be pressurizing the air that passes through it, so it would be running higher flow numbers and less pressure... which I think if you used the right turbos could keep them both within their max efficiency zones on their respective compressor maps, even when you're running more boost and flowing more air than the first turbo could efficiently do alone...

Now, this might be completely wrong, and might not work at all, but that's what I would try... maybe throw a couple intake temp probes in before, between and after the turbo's and large FMIC (not even an option, this is a must) to see what kind of tempurature changes the air experiences along the way....

 

[ChicagoGSX]

That won't work the larger turbo will be flowing more air and it will push its way back into the smaller turbo like I said causing it to surge. You just cannot run two turbos that have a large difference in size.

 

[FireyIce01]

That won't work the larger turbo will be flowing more air and it will push its way back into the smaller turbo like I said causing it to surge. You just cannot run two turbos that have a large difference in size.

I don't think you understand what I was saying... the outlet of the frist compressor will be pumping it's boost into the inlet of the second compressor... that would then run not the intercooler and to the intake... I don't see how it could push the air into the first turbo... I could understand how it might create a vacuum that would pull more air through the first turbo... but from the outlet of the second turbo, there's no way for the air to get back to the first turbo...

 

[leet]

I don't think you understand what I was saying... the outlet of the frist compressor will be pumping it's boost into the inlet of the second compressor... that would then run not the intercooler and to the intake... I don't see how it could push the air into the first turbo... I could understand how it might create a vacuum that would pull more air through the first turbo... but from the outlet of the second turbo, there's no way for the air to get back to the first turbo...

So you're thinking of having a BIG turbo pull air through a LITTLE one?

You do realize that is a major flow restriction, right?

Maybe I am not understanding your concept, could you draw a picture for me?