45 vs 41 rev limts.. vvt specs, injector sizes, exh manifolds??

[gdz1la]

i usderstand the 41 is more revalbe, but buy how much? is it enought to exceed the 45's flows without being unreliable? 4130cc vs 4494 ccwhats a safe rev limit on both engines? under boostwhat inj size does 41 have i have seen them being red which is 270cc? do the 380cc inj 45 ones fit?what is the vvt system like on the 41 how and where is it activated?and do the 45s better exh manifods fit on the 41 heads?

ia have found a cheap 41 to replace the 45 (i cant be bothered doing plastic guides) and the extra room with alt on top will also helpim not buying it until i am sertin the 41's revs superseed the flow of the 45anmd are most of the engines plus the same (i have wired up the 45 already)

(if it was a rb26 vs rb26/30) 73.7 vs 85mm) idd say go 3l as the longer rods also make a better rod ratio in the rb30.but with the v8's the 41 has a awsome rod ratio com pared to 45cheers

[mtcookson]

If you're going with a forced induction setup high revs really aren't needed. The higher mid and top end torque that a forced induction setup makes really negates the reason to do higher revs.

Engines tend to get less and less reliable the higher you rev them.

[gdz1la]

revs are a issue if i want big power gains,

my goal is 500rwkw on std internalsill be using the std inj...yes the 380cc ones ive got a mate with sr20 who got 280hp on sr20 with similar rev range so 560hp at std pressure or upto 690hp with adjustable fuel pressure prob arround 50psi at baro pressure. should give me the 500kw+ at wheelsill be using a greddy t78 33d 17cm housing or a t88 34d 18cm houingwhat turbo will be better and would it be laggy? or muffled up top? i used it on a 8.3:1 rb30det and it spooled good by 4500rpm (t88)

im guessing ill need 22-25psi boost and will be tuned on 98 or 100ron

i got 400kw on my 1st ever rb30det motor that was easy. rb26 head, big single turbo, injec and link ecu. so a v8 should be much easier and more reliable at high power.

will both 41 and 45 bottom ends hold up?are thety both as strong as each other?

[mtcookson]

I think you're under estimating the VH.

I've calculated about 10 psi for 600 hp (448 kw) with two T04E 50 trim compressors. Those should spool by, at the most, 3,500 rpm.

Glancing at the larger compressors it looks like the T78 and T88 would likely be way too big for what you want and those would likely take a while to spool, even with 4.5 liters.

I glanced at a T66 and that one seems to match really well with what you want. With that one you may need roughly 20 psi. Going by the numbers 20 psi would make about 720 hp (~537 kw) but I think those numbers might be a bit conservative.

(Those numbers are based on the VH45. The VH41 might need a bit more boost and possibly a smaller turbo (maybe a T64?) but for those numbers... you definitley don't need anymore rpm. You'll hit those numbers within the stock rev range.)

On the timing chain guides, they're actually very easy to replace, especially with the engine out. Not really that much of a hassle. I'm just replacing the two guides themselves on mine for the time being. Everything looks pretty good on it so I don't think it'll need the whole kit. Maybe when I redo the engine but I don't think it'll be an issue right now.

As for the injectors... at that power level I would estimated that you would need a minimum of 555's. 380's would be good (safe) for around 400 bhp at .65 bsfc, .80 duty cycle (kind of high), and 50 psi fuel pressure. For the power you want I'd probably try going even bigger than 555's to bring the duty cycle and the pressure into a safe range. Unless you're wanting to use more than 8 injectors, that would be the route I'd take.

I know the VH45 is a very strong engine. I don't know much about the VH41 but I would say that if it is much different, it wouldn't be much weaker than the 45... however the later Nissan engines tend to have more of a light weight setup.

The VQ35 for instance, has very thin rods to keep the rotating mass as light as possible, which makes for a very low stock power handling. I'm not sure if the 41 is similar to that or not. Hopefully some other guys that have messed with them will chime in.

[Mettler]

what inj size does 41 have i have seen them being red which is 270cc? do the 380cc inj 45 ones fit?

what is the vvt system like on the 41 how and where is it activated?

and do the 45s better exh manifods fit on the 41 heads?

ia have found a cheap 41 to replace the 45 (i cant be bothered doing plastic guides) and the extra room with alt on top will also help

im not buying it until i am sertin the 41's revs superseed the flow of the 45anmd are most of the engines plus the same (i have wired up the 45 already)

but with the v8's the 41 has a awsome rod ratio com pared to 45cheers

A couple of things. You're asking mainly USA people about the VH41 engine. The only VH41 motor they have experience with is the later version (94 onwards) where Nissan started cutting them down to save costs... eventually they even ditched the nice spider manifold !

The VH41 I'm dealing with is out of a JDM spec Y32 Cima (not available to the US or NZ market), and is a first generation VH41 motor. These are the best of them, with the big injectors, strong block, one piece bottom end, spider manifold, etc. Same spec as the Q45 engine, only the timing chain guides are metal, and the heads flow better. It's like Nissan fixed their mistakes with this motor.

I got some of my information from Mirage, who has been involved with the building of an 830HP NA boat motor (VH41DE stroked to 6L) here in New Zealand. This is an experienced person who has pulled these motors apart, and recommends the VH41.

My 41 doesn't have red injectors, they're grey. I'm sure they're the same 370cc (you keep saying 380 ?) rating as SR20DET.

The 41 has a different stud pattern on the exhaust side, so no, custom is your only option.

As I've said all along, go with the VH41... it will save you a lot of hassle and they rev harder. As far as I'm concerned the only thing more desirable about a VH45 (for a project motor) is the extra 0.4L displacement, hardly a big difference.

Also, yep the VH41 has a one piece crank/mains girdle with crossbolts through the deep-skirt block. It's just as indestructible as the VH45. I reckon both motors have an easy 1000HP bottom end... I personally would replace the bearings with greater clearance bearings, then up the oil pressure significantly, but that's all I'd change.

[Ezekial]

i usderstand the 41 is more revalbe, but buy how much? is it enought to exceed the 45's flows without being unreliable? 4130cc vs 4494 cc

Simple answer. No. Go the 45

Quote »whats a safe rev limit on both engines? under boost[/quote]you will find you wont have to rev it to high heaven to make power under boost. but since you are determined to put a big turbo on it then by all means rev it to 7200 or so "reliably".

Quote »ia have found a cheap 41 to replace the 45 (i cant be bothered doing plastic guides) and the extra room with alt on top will also helpim not buying it until i am sertin the 41's revs superseed the flow of the 45anmd are most of the engines plus the same (i have wired up the 45 already)[/quote]As above. The extra revs will not superceed the capacity advantage of the 45. Don't be fooled by the guide problem. Its a very VERY simple change mate

Quote »(if it was a rb26 vs rb26/30) 73.7 vs 85mm) idd say go 3l as the longer rods also make a better rod ratio in the rb30.but with the v8's the 41 has a awsome rod ratio com pared to 45cheers[/quote]Yes but look at the 45. Its already 1.78

Quote »revs are a issue if i want big power gains,[/quote]yes but in this example ... no. both rev over 7000 rpm

Quote »my goal is 500rwkw on std internalsill be using the std inj...yes the 380cc ones ive got a mate with sr20 who got 280hp on sr20 with similar rev range so 560hp at std pressure or upto 690hp with adjustable fuel pressure prob arround 50psi at baro pressure. should give me the 500kw+ at wheels[/quote]get that idea out of your head PLEASE!

Quote »ill be using a greddy t78 33d 17cm housing or a t88 34d 18cm houingwhat turbo will be better and would it be laggy? or muffled up top? i used it on a 8.3:1 rb30det and it spooled good by 4500rpm (t88)

im guessing ill need 22-25psi boost and will be tuned on 98 or 100ron[/quote]again ... get the idea of 25psi boost out of your head unless you are going to run 110+ octane fuel. Even then I really dont think the pistons are THAT good. Really ... i guess 22 is possible but certainly NOT with the injector setup you have in mind. For this boost and such high compression on factory internals you NEED nothing short of PERFECT control!!!!

As for T88 ... by all means if you are fine with going from about 250 engine kw at 4300 rpm to just shy of about 700 engine kw at 5000 rpm

[gdz1la]

thanks ezekial ill just tune it to the boost it cand handel tuners at work recon 20psi will be its limit.ill keep the 45 and get a price on guides ill post a pic when its sitting in bayill dial in 7500rpm as limit and see what the boost curve is like

[Ezekial]

ok so you want 500rwkw ... thats going to be a hard ask for a 4.5 litre with 98RON fuel and 20psi and still keep a respectable power curve.

but for arguements sake ... say 650 rwhp ... not far off 500 rwkw and its better to aim lower anyway. So find a compressor that will flow about 85 lbs/min at 20psi (2.36 = pressure ratio). Also the "wider" the map ... the better off you will be. Otherwise you will just get compressor surge until late in the rev range. Now the map i looked at might have been wrong but the T88 flows about 120 lbs/min at 20psi

yes i believe 20psi is the workable limit with factory camshaft profiles and factory pistons

GUIDES ... down the bottomhttp://www.trademotion.com/par...34381

[gdz1la]

would the t78 33d 17cm housing be better for it then?i got the engine in, the std headers air hitting the chassis rails how did you guys get around this?

[Ezekial]

check this re: headers

zerothread/179109

Here is some T** compressor maps. T76 down the bottom

http://www.turbofast.com.au/FlowTS.html

20-22psi boost. Dynamic Boost 18-20. I'll use 20 this time. So pressure ratio 2.50

Surge: 50 lbs/min @ 75%Peak: 63 lbs/min @ 78%Choke: 85 lbs/min @ 65%

Definately ON IN A BIG WAY at 3500 rpm

Would come close to the 500rwkw figure you are chasing but i think it would just fall short. Still a very good power curve though

[Ezekial]

FWIW ... these are the figures but using my GT4202RS

Surge: 35 lbs/min @ 65%Peak: 62 lbs/min @ 77%Choke: 88 lbs/min @ 65%

Similar peak and choke figures but see how its a much "wider" efficiency map (88-35=53 as opposed to 85-50=35)

http://www.turbobygarrett.com/...e.gif

[gdz1la]

so yuo think the t78 would be better for the einge?you have a 45 in a s12? did starter hit the steering coloum? if so how did you get aroununs this?

[Ezekial]

well i dont know but if its slightly bigger than the T76 then i guess that is what you are after.

I would go with the GT4202RS personally. Hence why i chose it