Has Anyone Got An Rb26 With A Single Gt35 On It?

[Gts-t]

  URAS said:

gate size is NOT related to boost it is related to exhaust flow, if it is too small you cannot control the waste gasses correctley and you will either get creep or the boost will climb indefinately, but as he has since corrected his gate size from 38mm to 44mm it is no longer going to be an issue.

as for laggy i usually compare the GT35R against the T67 8cm to my customers and the T67 will be on full song 1.2bar by 3500 and make 300rwkw no dramas i consider this not laggy 17psi on a daily street at 4200 is not exactly responsive. The Gt35R tho will provide more top end probaly around 30-odd rwkw to get this will a T67 requires a 10cm housing and cams (peaks about 340rwkw at 1.3-1.4bar). i do however agree though BANG for buck the GT35R is hard to beat and the extra lag and midrange loss for most is irrellevant cause they saved a bit of coin.... for me its a no brainer as we have both turbos on hand.

Hey uras,

where would a gt3040 .82rear fit into that ^^

Will be going on a 26/30 8.3 cr, high mount manifold, 44gate etc. looking for 300rwkw and running 1 bar max

thanks mate

[Shaun]

Hey 2630GTS, just wondering, but do you think that a CR of 8.3 is a bit low if you only want to run 14.7 psi? I can understand that CR if you want to use really high boost, but off boost it might be a bit unresponsive. Im not having a go or anything; just wondering what your motivation is

Shaun.

Also, what was the standard CR of the VL and RB26 engine?

[TTT]

Standard RB30ET is 7.5:1

Standard RB26dett is 8.5:1

Standard RB25det is 9.0:1

a 300rwkw 30/25 with 8.3:1 compression would be better off boost than all of the above.

[Gts-t]

  Shaun said:

Hey 2630GTS, just wondering, but do you think that a CR of 8.3 is a bit low if you only want to run 14.7 psi? I can understand that CR if you want to use really high boost, but off boost it might be a bit unresponsive. Im not having a go or anything; just wondering what your motivation is

Shaun.

Also, what was the standard CR of the VL and RB26 engine?

Hey shaun,

my motivation is that ill be putting this motor together and as it will be my first go i don't want to end up destroying an expensive piston and rod combo if i make any mistakes. It will be fun and good experience for the next motor i put together.

Also from what ive read from SK the rb30 should only get 1 bar of boost max to stay reliable. 8.3cr shouldnt be too bad, i think my rb20 at the momment only has 8.0?

Since i like to do things progressively and enjoy this so much as a hobby i will begin on a 3.1ltr forged bottom end after i know im happy with the characteristics of the rb30. If not i will most likely build up a 26 bottom end and see what thats like.

The car is built for circuit and i know there is only so much power a rwd car can use so limiting it to 1bar, 300rwkw, 700rpm should be ok.

[STATUS]

  2630GTS said:

The car is built for circuit and i know there is only so much power a rwd car can use so limiting it to 1bar, 300rwkw, 700rpm should be ok.

if this is the case you could get a faster combination out of something smaller.

[Wheezy]

  URAS said:

haha yeah made mid 350rwkw no dramas (other than uncontrollable boost) but the poor old girls catch tank looked like a kettle on full boil at 1.5bar tooot tooot

Looked like a disco smoke show the last time I saw it on the dyno with the garrett

[R31Nismoid]

And there be the daily stroke

[Gts-t]

  URAS said:

if this is the case you could get a faster combination out of something smaller.

What would you suggest uras?

[Roy]

Do 3040s really make all that much more power then the GT30R??? I have a HKS low mount manifold so i am shopping for a single for an RB26...so general consensus is GT35R is too big....so what else is in the ball park of being able to muster 360-390rwkws using about 21psi,

[discopotato03]

Roy if you have a HKS cast iron low mount manifold for the RB26 it will be T4 flanged so a std config GT3582R won't bolt up . ATP (US) I think were doing an open (SS) T4 flanged housing for the GT35R in I think 0.82 A/R .

If it was a drag engine I'd suggest a GT4088R in its normal TS form and with a HKS or equal external gate . Actually those manifolds are supposed to have a short stub pipe that angles the WG backwards and is 3 bolt at the manifold and 4 bolt at the gates base . They also use (from memory) a 50mm valve size which is not the most common in HKS bits .

If the 88R is too big then possibly a BB T4R which is P/60-1 or a T04Z but thats starting to get big again . At least there's plenty of TS T4 turbine housings to play with .

Your call but I don't like the GT3082R (AKA GT3040R) , too much comp for the turbine so they tend to be laggy .

Cheers A .

[Wheezy]

  R31Nismoid said:

And there be the daily stroke

You stroke mine, I stroke yours.........

[Snowman]

I've driven a GT-R with a GT35 on a built RB26 and I thought it was tripe. Way too much lag - was a bitch to get around the track. The car was making around 350awkw's. The same car with a GT30 making 300kw's was so much nicer to drive.

[STATUS]

my point exactly. ^^^

[Roy]

  Snowman said:

I've driven a GT-R with a GT35 on a built RB26 and I thought it was tripe. Way too much lag - was a bitch to get around the track. The car was making around 350awkw's. The same car with a GT30 making 300kw's was so much nicer to drive.

Kids these days. Want to do everything the easy way. In my day you had to work for your laptime and drive through the many compromises in the car.

And Disco...yeh, thats the one, i am happy to machine up a T3 flange for it if need be...though i do like the idea of a T04Z

[DCIEVE]

hmm went 35r over a t04z because I didnt want a silly amount of lag (even though 90% of people seem to be going the t04z route) and you guys are saying even thats too big for a 26?

roy, I did plenty of looking and found most guys with a 35r on a 26 were making 375-390rwkw on 21psi (on song by 41-4200rpm) - with the higher numbers coming with poncams and larger exhausts (3.5") and the lower end with stock cams and the usual 3" system. If we can make those numbers with a smaller turbo im all ears

Edited November 23, 2007 by DCIEVE

[Gts-t]

What would be the go on a 26/30 for 300rwkw?

uras, disco?

[discopotato03]

Tripe yes I can understand that . Sorry the broken record - when you remove parallel twin turbos and replace them with a single scroll single turbo technology wise you've taken a sizable step backwards . Parallel twins operate exhaust wise very much like a single twin scroll turbo . With twins its 123 - front turbo , 456 - rear turbo . With the TS single its 123 - front nozzle , 456 rear nozzle .

If you bolt on a single scroll single turbo its 123456 - single nozzle .

I'm running out of ways to explain this but one more time . When all six cylinders communicate with a single passage exhaust housing the average pressure within the housing WILL be higher . Any pressure rise down stream of a performance engine is THE enemy . Splitting the exhaust plumbing on an I6 as mentioned above means each cylinder firing event alternates between the front and rear groups because the firing order is 153624 ie front back front back front back . Now because the front and rear groups can't communicate (till the gasses enter the turbine blades) the time between the firing events is double for each group . Because the time gap is greater the pressure in each passage is lower just before the exhaust valves crack so there is LESS resistance for the firey gasses between the exhaust port and the nozzle . In other words more of the thermally excited expanding gas velocity is available to drive the turbine .

Also because the next exhaust event is via the other group the current cylinder has longer to blow down to a lowish pressure in this same are before the current group get its next blast of exhaust . The overall result is high manifold pressure when it needs to be high - exhaust gas to drive the turbine , and low pressure when it needs to be low - best situation for the next exhaust event .

Roy , that RB26 manifold has larger passages than the 20/25 version and the outlets are probably too large for a split T3 (T4 Euro actually) flange without copping a pressure drop . If you want to run a T3 or split Euro T4 then the 20/25 version will work better . The 20/25 version is a sort of hybrid because it has the split Euro T4 sized outlet ports and stud hole pattern , the flat pad they are in is actually the big T4 size . In other words it can be converted to true T4 size where the 26 version is already the big size , your one was designed for a TA45S turbo which is basically GT4088R dimensions . The 20/25 version was designed for either a full sized T04E or T04S , by full sized I mean T4 turbine and housing . Dimensionally those two fall in line with a GT3076R and a GT3582R .

Also as I sure you know the head side stud patterns are different RB20/25 vs RB26 , I smell a sleeper here somewhere Roy ...

300 kw 26/30 ? A set of 2530's would breeze in 300 Kw you'd think . Boost threshold ? Hard to guess but assuming a std capacity RB26 gets on song at say 4000-4200 , if you put 20% more capacity under it then in a simplistic way could you expect it to load up from 20% less revs ie 32-3400 rpm ? So many variables .

Twins would be convenient because the two integral gates are part of the package , the twin scroll single chains you to an external gate or two if you go the most effective TS route .

So unless you have lots to spend twins have a bit going for them , they can look very std too .

Look at the time , I'm outa here .

[Shaun]

  Snowman said:

I've driven a GT-R with a GT35 on a built RB26 and I thought it was tripe. Way too much lag - was a bitch to get around the track. The car was making around 350awkw's. The same car with a GT30 making 300kw's was so much nicer to drive.

I wonder why my car with the gt35 (0.82) made boost way too early then?? It was making 1 bar at 2000 rpm and was uncontrollable. Thats why i went the 1.06 housing. It'll be interesting to see how that goes.

Shaun.

[Lithium]

  Snowman said:

I've driven a GT-R with a GT35 on a built RB26 and I thought it was tripe. Way too much lag - was a bitch to get around the track. The car was making around 350awkw's. The same car with a GT30 making 300kw's was so much nicer to drive.

After reading various turbo threads from Oz, I am truly perplexed. Maybe you should all get XR6-Turbos or maybe Supercharged V8s!! I've driven my mates R32 GTR with a .82a/r GT3582R and its building boost in the 2500rpm range and by the time you reach the revs the stock turbos have reached full boost the thing is pretty much ready to hit warp factor 9. It DOES have a big turbo feel below 3000rpm but phooey. You don't buy a GTR to show how good it can tow.

[R31Nismoid]

Ye but compared to the setup snowman has now with virtually similar power, thats how you notice the difference