What about a momentary pressure drop at the 1st turbo during transition??

 

Interesting information on a sequential turbo system.

 

Call Rob at Extreme Turbo Shop ... he is in Lakeland, FL close to me here. I have talked to him about this before and he said that he can source the parts ... the guy knows his stuff.

He is in the process of building a twin PT106 540ci big block right now with the intention of running 5's in a doorslammer.

His number is 863-647-3700. www.extremeturboshop.com ... there are pics of his older mustang on there, but not his new one.

 

what about an eaton blower? it actually seems less complicated to have the turbo discharge into a blower. Very very common in big diesels.

 

thats exactly what i was thinking of except most electric cut outs wouldn't take alot of use like what i am thinking about.

i think going to twin 72's even with the ball bearings i will still have more lag than the single pt88 i have now and that is too laggy. i took alot of the fun out of my truck when i went from a single 76 to the 88 even though i gained 350hp. i am looking at geting the fun back AND gaining more power.

that squential set up is a neat idea but the big turbo would have to be a monster like a 94mm thumper for the power i am looking for. that means a huge down pipe.

the flapper on the intake side of turbo 2 wont open untill there is sufficent presure to push itself open. it wont have any control. just consider it a oneway valve. the exhaust opening to turbo 2 will reduce the volume of air to turbo one and may cause a momentary platou in boost till the 2nd turbo spools up. i think it would be smooth if the gate was opened at just the right time and at the right rate. that would take some fiddleing.

1/10? i dont see that at all. first of all i do not want a single turbo. i would need a huge single to give me the potential i am looking for. last i checked a thumper isn't much of a cost diference from a pair of 72's. with my initial idea i could get by with one waste gate and the only extra parts would be a oneway flaper valve in one intake pipe and some kind of exhaust block off in one of the up or down pipes. about 2' of extra pipe. i think i can do this for about $700 more than a complete twin set up, not that much even if it fails i am not out that much.

now back to the real questions.

1)will it rudece lag, i think it will at least initial lag. i shoul be able to get from idle to 600rwhp very quickly.

2)will it still have the same top end potential, i dont see why not as long as the down pipe gate is not a restriction at all and a sliding full sized gate would not be a restriction at all.

3)the real question, will i be able to make the transition from a single to twins seamless? and will my the total time to full boost(~30psi?) happen any quicker or actuly take more time over all?

i want twins for a few reasons. one is i can put real air filters on them, another is i can get twin 3" exhaust on my truck easy but a single 5" would be a pain. twins are cool looking. i will be doing twins. that part of my research is done

 

Parish.. Try one of these intstead of the electric cutout idea.





I will be running these on my car. They work off boost. The open almost instantly with almost no boost. You can control where they open with a manual boost controller. PM me if you want more info.

 

that does look like it would do the trick. i bet it opens fast. do they make a 3" version? it also looks prety durable.

 

Negative...I've seen it done many times. One prime example is Chris Chow's car. Chris' car runs 2 - 70 series turbos on his under 400 c.i. (edit: chevy dry sump v-8) Buick Turbo Regal and it has now run a best of 7.97 in the 1/4. Call Fasttrackperformance.com ...or even call Precision Turbo. They own/build/supply parts for some of the fastest turbo cars out there - bar none.

I will be installing 2 - 67mm dBB turbos on a 370 c.i. motor going in a '99 T/A. They will push hard and make good power. It's all about the combination and sizing.

Twins turbos are cool, twin blonde hotties are even better.

 

ok, maybe not 1/10 the cost...but 1/10 the effort and frustration and labor costs.

Maybe I just don't understand the goal here? Why not use truck manifolds? Why not run ball bearing turbos? I get you want to run a twin, I'll lay off the single stuff. But logs and a sequential setup IMO are a recepie for disaster...unless you make the log material .5" thick. Id do something like that porche set up above but with iron manifolds and the biggest wastegate you can find.

 

what would a huge sudden drop in exhaust back pressure cause?

lol hell heres what you could do, set up an electric cutout on one of the downpipe. Keep it closed for street driving and have one tune for that(backpressure should affect the tune). Then open it up for the track and have another tune for it. (My EE side keeps telling me that current travels in the path of least resistance but i dont think that works for turbos.)

or find a pwm signal off the ms(IAC stepper motor may work, not sure), then use that to control how open the cutout is, gradually decrease it in a percentage function, then rewrite your ms with new code like the LS1 Low and high octane tables, with a scaler function between them. Find the relationship between how far you open the cutout and how much more fuel you need and have a table between the cutout open percentage and the LS1 style octance scaler function. IONO just throwing out ideas.

 

Parish,

That is a 3" one I will be going from a 5" downpipe to dual 3" and placing these before the mufflers.

 

lil did you know that the 5" downpipe will flow more than 2x 3" downpipes. 2x 3.5" will get you closer to, and almost the same amount of flow as the 5"

 

if i were to do it i would do it this way...

it is the closest thing to any other "factory" type system out there...porsche did it in the pic on this thread and from the looks of the mazda pic that is how they did it as well.

Just have to block the intake piping...use a staggler valve(whatever that is) it seems to be what the porsche is using.

Louie

 

I am aware of that. However, on the street it will have to go through 3" exhaust and at some track events it will were a straight 5" downpipe.

 

Yes, space availability could be a problem for big turbos and I have to agree on a equal size twin turbo that give a nice symmetrical aesthetic look in the engine bay.

For those interested, here's some pictures of BMW sequential turbos diesel engine based on the same Opel's diagram.

Article link : http://autospeed.drive.com.au/cms/A_2544/article.html

 

lulu that the 3.0ltr diesel used in the 535d right?? i have heard its AMAZING!!! and even better if you let some guys chip it for you! hehe i think they are making 450lbsft and will do well over 30 to the gallon even when giving it some! hehehe

anyway great find!

i think yu will see more VNT/VG turbos coming on the market for petrol engines! they are starting to come through now. the only problems with these butties is they requier complex electronics to control them! the sequential system above looks all manual!

Chris.

 

How about using the same idea but apply a third turbo to avoid the drop in boost. With three turbos each responsible for a different rpm range you could have a car with 1000hp but still have the boost characteristics of a blower (boost from idle up) but without parasitic loss and it just might be the formula for the best street/strip setup out.

 

i am trying to keep is as simple as i can.

right now i think i will step up to the ball bearing t72's and see how how laggy it is. i expect it to be worse than the single pt88 but if it is better then why bother. if it is the same or worse i will give the simple sequential idea a shot. just one block off valve and a one way valve should be all it takes.

 

But just think of the possibilities of three or hell four turbos in sequence. I'm not convinced it's that complicated either.

 

Have you asked Tiago when he spools? He's got twin MP T70's on a 346 w/ less weight than you. EDIT: AND a six-speed.