For any of you guys with a T34/0.48.......

What rpm is the boost threshold generally and when does it run out of puff? How do you find it for driveability?

I'm on a T34/0.63 at the moment and it doesn't start pulling 'till about 3200rpm the engine is only 7.5:1 CR and feels too sluggish low down (could that be mapped out with more ignition?)

Was hard work keeping up with an ST170 on twisty roads no long ago!
So I'm thinking of going down a housing size.....

803's
RS200 spec intercooler
std head + cams
3" exhaust
1.5 bar held

 

No too sure about the rev range info but I have a 34 with a .48 housing, it does spin up quickly and is not laggy, where as .63 .55 you have to wait a bit for the boost


Luciano

 

Im no expert but I looked through my pectel datalogs and found one where I boot it in 4th gear at 2500rpm.

By 3200rpm it got full boost ie 1,6bar.
It then hold this and actually creeps a bit higher to around 1,7bar and it isnt until around 5500rpm that it starts to tail off very, very slowly. By 6400rpm it still holds 1,6 bar.

 

Thanks guys, that sound ideal, I dont generally take the engine past 6000rpm. What injectors are you using?

pete

 

Its a standard compression engine using 803's but im switching to bigger siemens injectors for next season. I don't like to rev it either so for me its ideal.

But you better ask for some more opinions as I don't know much at all.

 

I have full boost by 2700, all held very well at 1.9 bar till about 6500, near it's 7300 soft cut.
Mapping will make a world of difference, especially off boost, mine doesn't feel as quick but that is because it has no sudden increase, as there is not so much lost power low down now, as it has more so not such a step, onto full boost.
Mine is on greys and std cams but modded head, only light modding on exhaust ports.
I noticed when it was mapped, it has loads more advance now.
tabetha

 

mine made 36psi at 2700, they do run out of puff at the top though

 

Ta guys,

What approx power are you likely to get using the 0.48 ?

Tabetha, do you run the greys with the pintle caps off? I remember reading somewhere that its preferable to do so.

Does anyone know if the 0.48 housing a straight swap in place of the 0.63 or is there some engineering involved?

cheers

pete

 

straight swap.

370-380 is absolutly flat out, and turbos become knackered at about 30k miles before they need rebuilding at that.
and the exhaust housings crack due to the constant heat battering

 

harsh sig so a .55 should be able to push 380-385 with out stressing it out to the max?

 

maybe....ive never tryed a.55

 

never tried a .55! you aint lived until you have!

 

I have a .48 T34

hit boost by 2300 and full chat (1.6 BAR) @ 3100prm

have a slightly ported head and 7.8:1 pistons.

Drives very well and doesn't run out of puff over 5k like a T3 but you won't have the lag of a .63

 

if you dont rev the tits off it or track it then the smaller .48 will make the car much nicer to drive daily

 

I have tried with the caps on and off, I didn't find any difference, but will put it on the rollers again to check, also going to check airbox versus cone/cone with shield.
T34.48 will do more than 380 without problems, CR turbo's man used to run this on his 2wd cossie, but lightly ported head, works wonders on these particularly at top end, where as said they don't tend to run out of puff so easy.
I am going to a T34, with a .60 ar comp housing as I have std T3 comp at the mo machined out to take t34 trim, so it has an easier time.
tabetha

 

Tab,

am very interested in the cone v air box test. Make sure you post the results bud

 

Before you do ANYTHING, take it to Martin Hadland and have the map checked over. Recently he has managed to get 30-40bhp AT THE WHEELS by optimising the "off the shelf maps"!

Once you have done that, you can then try the car in it's new format and see if you still find it wanting .

You may find that the injectors are running out of duty cycle, but a switch to greys would give 320bhp at the wheels with the spec you have .

 

No wonder you're loosing out to ST170s then . You should be revving to 6500 in EVERY gear.

 

Do NOT use the greys with the caps ON and high boost, or it WILL melt .

 

It should start pulling way before that!!

Btw.. What ECU is it running?

 

Oddly enough this is why it is done on the rollers so it can be checked.
tabetha

 

Its probably a combination of me being a shit driver and the crappy ratios in the renault transaxle!

Its on an L8 ecu Martin, I think its an A1 rallysport chip in there. It was like that when I got the car.
It will make +ve boost (approx 0.5 bar) below 3k rpm but doesnt really get going till about 3200rpm

Another thing I notice is it seems to pull better on half throttle than full throttle when on boost

 

Do you know the chip is correct for your engine spec? I would suggest going for Siemens injectors and a remap, I can do this on our DD rolling road for you and would provide a print out of before and after.

 

You may find that your generic off the shelf chip is basically shit for your engine .

 

Yep, I agree

Whats better about the siemens injectors compared to 400's or 403's ?

Was thinking about going closed loop and wasted spark while I was at it.

 

Just the fact that their higher flower gives you scope to increase the power at a later date, with one less thing to have to change - as in, they have a much greater ceiling of power.

400s around 400bhp LIMIT
403s around 450bhp LIMIT
Siemens blacks around 500bhp IIRC

 

So to dispel any myths, its nothing to do with a better spray pattern/ fuel atomisation etc then, as long as the car is mapped correctly for whatever injectors are being used?

thanks

pete

 

Correct, although the Bosch 400s do have a nicer shaped spray pattern than the 403s . However, careful mapping will get the best out of all injectors .

 

Always wondered if that was the case.

Ta Mike

 

Some people have had problems with emissions on Siemens, and have gone back to greys etc to get the car through the mot.
tabetha

 

and some havent.....greys are fine for pony power lol


ive never seen a .48 make more than 380, i had a good spec motor on a .48, we made lots of mods during it life to try and gain, and gain, and come the end i could have welded the wastegate shut as i was using every ounce of air it could produce. they simply make power to low, and ultimately dont flow enough air to make more. The compressor map and simple physics tell you that.

i even had surge at 36psi, which was the restrictive neck on the plenum, so ran a swedish to overcome it.

unless its tdi rollers

and they do become "consumable" items running 2.5 bar, as i found out several times. one of those being from cr turbos.

im sure they would last longer if you drove like a fanny though

 

im on t34 .48 with a norris gunship been good but just bought some greys and will be going back to karl yo get him to work his majic again
only problem i have with it is that sat at 80 its spooling up so seems to use a bit of juice on runs weather bigger housing would change this i dont know

 

yes it would....

i can cruise in closed loop at 110mph with the T4....

 

We just need someone to manufacture a reliable VATN turbo for petrol engines then we'd all be sorted!

I don't think theres many new 911 turbo ones kicking about though!

 

What u mean by using grays with the cap on will cause it to
melt

 

Which part of the statement did you not understand ? (however, please note I did qualify the above by stating that if you are running lots of boost - on a T34 0.63 - as in pushing the turbo it it's physical limits)

 

Presumably because they're will be more air than fuel, which = lean = heat = melted engine.

 

In which case it would be noted on emissions, so you'd be fairly silly to run it like this as you would know the likely outcome beforehand.
I don't know how much bosch know about injectors though.
tabetha

 

They know "quite a bit" , but can't be there looking over the owner's shoulder to make sure they are using the correct rated injector for the specific application .