How many horses can a stock internal RB26DETT take?

[mtam22]

Guys, I'm at a cross road on what to do with the 32 GTR I just bought. The previous owner swapped out the original 2.8 litre before he sold the car so I'm left with a setup as follows:

Stock engine in very good condition

Pair of Trust TD05H-18G with twin downpipe and wastegate

Matching twin entry Trust intercooler for the TD05Hs

Stock fuel system

Trust mechanical boost controller running 1 bar

Greddy AIC but disabled and injector holder removed

Trust ECU allegedly programed for stock system and need to work with AIC

Turbo lag is horrible with this setup with no boost in 1st gear until 5,500 rpm. Engine willingly spins to 9,500rpm.

I'm undecided between the following options:

1. Cheap option and keep TD05H -- Get 264/264 cam, upgrade injectors to 550cc and Tomei ECU matched to this setup. Up boost to 1.4 bar. Leave engine standard.

2. Expensive option and keep TD05H -- Get a ready built 2.7litre engine with forged piston, N1 oil pump and N1 water pump. Stock conrod, stock crank with new N1 bushings. Turn boost up to 1.6 bar. No money left for cams

3. Dump TD05H and revert to stock turbos or upgrade N1 turbos -- Need to replace intercooler plus all piping. Upgrade to 550cc injecto and turn boost up to 1.5 bar. Fast response, lower top end and wasted the TD05s.

I want a street car not a drag car and need to lower the boost rpm to around 4,500 rpm. Are the TD05s capable of boosting this early? If I leave the engine stock, how many horses do you think it can take?

[fatz]

just get it tuned for 1.5 bar

that should keep you happy for a while

probably not a good idea to rev a stock bottom end to 9500 all the time as well

pete

[maximumrpm]

id say about 500-600hp...if its internally stock, but give it a clean and change the head gasket

[mtam22]

Would 264/264 cams go well with the TD05Hs? Where can I get the smaller 16G housings, how much, and do I need to change the turbines as well?

I've got two camps of friends giving me opposite advices. The N1 camp advocates dropping the TD05Hs. Pros they stated are:

1. Faster spool up, lot more fun and usable on the street

2. Engine wear will be a lot less severe than TD05Hs even if the N1s are run at 1.5 bar because power delivery is more linear and less brutal than the TD05Hs

3. Easier to control fuel

And on the other corner... the TD05H advocates:

1. Easily double the power of the N1s

2. It's already on the car there's no point purchasing all the stock manifolds, intercooler and downpipes again

3. Horses for courses, a high revving TD05 GTR will supplement my mkiv TT which is more suited for low/mid rpm street races

The shop that sold me the car will take back my engine in excellent condition engine for apr. AUS$1,700 and sell me a used but also excellent condition 2.8 lit (Trust piston/Trust conrod/N1 oil pump/Nismo water pump/ ported head with 264/264 cam) for apr. AUS$5,000. Seems like the 2.8lit is a much safer platform to build up my R rather than spending the money on N1 turbos don't you think?

[rb26dett]

like u said u want a street car. now if u were building a drag weapon, i think the TD05 should stay on...

for a street car, i'd think the N1 turbos would be more than sufficient to do the job.

u're in H.K. right? get it tuned with someone who's good there. they know how to tune the F-Con Pro right? get the fuelling right and of course, the cams too. if you can't then just take it one step at a time, or save up and do it all at once.

the 2.8 would be a good engine, but dun think u'd need it with N1 turbos. unless u're planning a track car, dun think u'd need to get so extreme.

again, for street-trim, i'd go with N1 turbos. much easier to live with and work with. dun forget, these turbos see the JGTC cars produce 500 odd horses...so they're not that slack too

[Sydneykid]

Hi mtam22, I think a TD05 compressor side is a good size for a tough GTR. As merli suggested, check the turbine and housing they may be too big. I would suggest a pair of 256 hi lift (around 9.7 mm) camshafts, 264's will be too peaky. Dial in the camshaft timing for stronger mid range with a set of adjustable camshaft pulleys, again as merli suggested.

Get an Apexi Power FC and have your tuner optimise the whole power band (particularly ignition timing), not just tune for max power at one spot.

If that is heading in the right direction for you, and you want some more, then wip the head off and have it ported a little bit. Ceramic coat the combustion chambers, exhaust ports and primary exhaust manifold pipes. This will help speed up the air flow and retain some heat, which will spool up the turbos a bit faster/earlier.

Do the numbers, if the engine current spools up at 5,500 rpm with 2.6 litres it will spool up at 5,300 rpm with 2.7 litres and 5,100 rpm with 2.8 litres. Hardly worth the trouble/cost.

Hope that helps

[mtam22]

Thanks for all your advice. More questions. Would a high lift (say 10.5) cam help spool up? My car' comes with a mechanical Greddy boost controller and I wonder whether installing an electronic boost controller may be a more effective way of ensuring that there is no leak at the wastegate at lower boost pressure?

How safe do you think I am running the N1s or HKS Kansai GT-SS without laying a finger on the engine's internals?

Rgds

Michael

[Sydneykid]

Hi Michael, hi lift (narrow duration) camshafts will help spool up. I would get the Power FC with the boost control kit. That way you can control the boost rise with Commander. Works out cheaper than an equivalent quality, stand alone, electronic boost controller.

The TD05's are OK as long as you keep the boost low and tune it properly. N1's would be no different. If you are looking at changing to HKS turbos, then 2530's are without doubt the best all round twin turbo set up for a GTR. Spool up as quick as standard turbos, give great mid range and super top end.

Hope that helps.