reducing spool
 

with more of us starting to run bigger turbos, this subject needs to be addressed. on my setup, it doesn't start ass hauling mod untill about 4500rpm. what are somethings we can do to reduce spool?

everyone knows the better flowing exhaust the better. i plan on porting my turbo exhuast houseing, that "should" help a tad, i hope. but is there anything else to do?

does charge pipe diameter affect spool? intake going into the turbo? port out the exhaust ports/mani inlet? anything worth doing?

anything that has to do with air getting into/out of your engine effects spool

Smaller turbo LOL.

Anything that improves VE in the RPM range in which it spools. In your example, 3500-4000 RPM. For example, cam timing changes that improve torque in that region.

And advancing the exhaust cam so it opens earlier.

A 50 shot would wake it up :D :nxsmile:

after feeling the jet thrust up top, that is not an option :noob:

make it rev to 9k...that'll make 4500 seem relatively low RPM...;)

What's your peak power?

BTW I've had a turbo miata since 1998. You? :noob:

Intercooler with less pressure drop
cam/ignition timing
fuel
manifold design
exhaust design
intake design
improved efficiency

have fun.

Are you saying that the boost doesn't start a steep rise until 4500? OR it doesn't hit target until 4500? If it's the latter- that's pretty good spool for a decent sized t3/t4 on a 1.6 IMO.

You need to find out what exact specs are of your t3/t4. Smaller ARs are a relatively simple way to change spool- and smaller is cheaper in the world of t3/t4... especially on t3. You could even go as far as putting a big t3 compressor on.

also, the people who like the jet thrust feeling at 4-5K, would probably also like the same feeling at 2-3k :giggle:

Head work is the biggest thing you could do. (reducing spool doesn't sound right, don't you want to increase it?) Porting makes a huge difference when done right and will add power everywhere and help spool and increase the usable rev range by increasing VE at the higher RPMs. But you'll need a book or two on porting to know what to do.

http://www.shoremotorsports.com/pics...ownpipe5TB.jpg

Having a dp like that should help.

I'm not sure why pics on the shoremotorsports server require a reload to show. :(

when you say "porting my turbo exhuast houseing" what exactly are you talking about? Hopefully not the wastegate passage

porting is common in the dsm crowd, basically the inlet of the turbine housing and exhaust manifold are opened up/matched

How bout we just call it "improving spool"

How bout we just call it "Lowering Boost Threshold":giggle:

Pshhh (pun intended), you wouldn't know what boost is. ;) From the south we call it "makin' her get on down the road".

this thread sure did bomb. but i am reaching full boost about 4500rpm.

Gain 10-25% more power and drop spool 500-1000 RPMs.

http://books.google.com/books?id=283...um=1&ct=result

The starion can't be helping - 20 year old tech.

What mani, exhaust, cat, IC piping, route, etc. are you running? Pics?

the intake sure does. i remember testing with and without my intake assembly (stock subaru intake pipe, cheap cone filter and bypass pipe) and remember the threshold being about 250 rpm lower as well as spool being much faster in the range between 10" Hg vacuum and 2-3 psi boost.

ebay cast mani, 2 1/2 inch downpipe doing to a 3 inch exhaust, no cat, 2 inch hot side and 2 1/2 coming out of the intercooler. and the air filter is right on the turbo.

hell yeah, free bitches!

thanks man

That only has the first few chapters. All the good stuff is not shown. But it's a good read none the less. But all the good info you need to know is not shown. I just bought a copy of that and another book about building short blocks by the same author.

And yesterday you couldn't stop calling me a dumbass or picking over semantics.:bang:

that's because i am a dick, lol :fawk:

Might want to fix that. I had mine there for a while, sucks the hot air right off the manifold. I put a 90 degree bend with the filter on the end. It made a noticeable difference in power.

bryan you didn't answer the Q about how much peak power you make.

well even with my filter on the turbo, i only see a max of about 130 IAT under full boost.

jason-i have no idea how much power its making, never even touched a dyno.

Depending on your peak power, there may be smaller turbos that can give the same peak power, while moving your desired "jet thrust", down from 5000 RPM to 4000 RPM.:giggle:

You also didn't answer how long you've had a turbo miata.

i have been turbo for about a year now. i was actually going to go with a 16g or a standard t3, but i got such a good deal on this turbo it was impossible to pass up. real turbonetics just rebuilt for $100 :cool:

what is "full boost"? 5psi? 15psi?

right now about 12psi.

it was make just a couple of pounds in the lower rev range, but about 4300rpm or so, it just jumps 10psi instantly.

its kinda fun, its like
lag lag lag lag, .....OMG!

My old setup would make 6psi from 3000 on up to about 4300. At 4300, It would almost instantly go to my boost setting...be it 15psi or 28psi. I had very little lag when I was above boost threshold.

http://www.boostedmiata.com/dynos/matt_vs_tim.jpg

choose your weapon.

jeez use my lamest run. use run 5.

Ah, so you're the newbie, dickwad. I've been turbo'ed for 10x longer than you. You just discovered the reason I advocate, for a street car, the smallest turbo that meets your realistic peak power goals. Unless your revs are always above 4500, you'll be caught flatfooted if you need power NOW.

If you do headwork or some other changes to greatly improve spoolup, you will likely spend more than the money you saved on your $100 turbo. Even then the improvements will be less than switching to a smaller a/r housing or smaller turbo.

Sell your turbo to some other sucker who wants "jet thrust" at 5000 RPM and put the money to a smaller T3. Markp's favorite T3 config is good for 300whp and spools close to a '2560.

Mark told me all about his 300whp capable turbo. Said full boost was at 4500 RPM. I do believe most 2560's are in full boost before that. Maybe Mark needs to clear this up.

Now I understand a lot of people hate lag. I do too. However, some people hate having a motor with no "top end". I'm one of those guys. I'm gonna put a big t3/t4 on my 99' because I want some top end power. I'll take the lag for the top end power. Granted I'm going for 350whp. Still, there's probably smaller turbo's that will get me there, but I'll pass.

it's just to illustrate the point.

who's got a 2560 cheap? nobody? ever?

wasn't mark running a standard t3/t4 chinacharger?

i might try and find a cheap t3 and throw it on and see how i like it.

just find the compressor housing, back plate and wheel...

hmm i could pull those from the junkyard.

but would't i need to the the center balanced when swaping wheels? if not, i will deff try that route.

No, it was some fairly common T3.

The last turbo he had was a t3/t4 (300whp) but that was with a big "money" head and lots of revs. A big t3 is the way to go IMO... and you're half way there. I've seen the cold side ford 60 trim pieces come up on ebay several times.

my turbine has had a 50 trim t3, t04b-s, random ebay 50 trim, and a t3 super 60 wheel on it at one point in time....

a few weeks ago i just had to replace the turbine shaft...think I got it rebalanced? ;)

cool deal then. i will keep my eye out for a T3 of some kind then.

dam i love the low end TQ on that twin turbo power graph. i love TQ the more the better well untill you start breaking stuff.