VH45DE questions

[1992Q45A]

What a godly car...

Anything TWR touches is gold

[450sxtc]

Ok, first I want to address the quench zone. You're right about the hot spots. If you left the head as is, it would creat hot spots. There are 2 things that could eleminate this. You could use a dished piston with a taller compression height. You would have to raise the compression height of the piston by the same amount that you decreased the length of the rod. The only problem with this is the chance of getting cold knock or the piston rocking in the cylinder and damaging the cylinder walls. That could be prevented by using a really deep dished piston but then you'd be dropping the compression ratio to much. The better way to prevent this (in my personal opinion) is to retain the stock compression height, and polish the elongated sides of the cumbustion chamber. Possibly even machine them out some and de-burr the edges. This will drop the compression ratio a good deal also, but if you were to round and polish the combustion chamber and then use flat faced and swirl polished valves (instead of the stock domed ones), it would open up the quench zone even more and still mantain proper compression ratio. Also, as the piston rises in the cylinder, the compressed air will be forced through the quench zone and then across the valve faces toward the center of the cylinder. This will cause a collision of air in the center of the cylinder where the thick part of the dome of the piston is at. The collision of air will give good turbulence and as the combustion pressure pushes the piston back down in the cylinder, the heat will be absorbed by the uppermost point on the dome of the piston and spread down the piston as the powerstroke occurs. Then, when the piston reaches bottom dead center it is sprayed with oil at that point to help dissipate heat. As far as the compression ring, I think that a set of Gapless rings would work great in this application. Also it could work to use a forged piston with the with basically stock measurements and have the pin height increased the exact same amount as the compression height, which in my case would be .080". So the piston would be .160" taller from top outer edge down to the bottom of the skirt. This would allow for a top ring that's about .010" + or - thicker that the stock and give you the same size ring land and a taller upper ring land.As far as saying what motor these rods are out of........I really don't want to b/c I have studied this motor so hard to come up with a way to make it stronger. What I can tell you is that the compression is going to be about 8.01-8.14:1. Also the rod ratio will be righ at 1.75040 and change, and yes, they ARE forged. They are avaidable in I-beam H-beam and X-beam. With this particular rod, the crankpin bore has to be resized and the sides and rod radii have to be shaved just a tad. The piston pin bore is just big enough to bush and allows the use of a full floating or pressed pin. It's up to you andthe machine shop. I will give the stock rod lenght CTC. It's 5.7854-5.7868. Work with that and see what you can figure out. When you figure it out, don't tell, because if you do it, IT"S GONNA HAUL ARSE!

[IvoryJ30t]

thats a touch too low on compression. id rather have it at 9 flat. dishing the piston slightly more would yield the best results. i want to have the compression relatively high to make up for the low end im gonna loose by advancing the exhaust cams 10 degrees or so to pull most of the overlap out. on top of that, the stock intake is tuned for 4000 rpm in N/A. that would give me nice midrange, but on boost at higher rpm, the motor may not like it. i have a design for a new intake manifold, and converting the injectors to top feed from side feed. i just dont know how that is gonna affect low and midrange power. after all, i am going to be hauling a 3500 lb car around with this motor.

i wish i had a multi million dollar R&D fund...

[IvoryJ30t]

450 wheel horsepower and a manual transmission is 530-550 at the motor. thats borderline between just boosting the motor, and doing rods and pistons. whats the point of turboing it if the motor wont tolerate more than 20-30 seconds of boost at a time.

optimally, id like rods, pistons, maybe the intake [to make hose access and injector/fuel rail access easier. i would fab up a new manifold, just to get rid of that nightmare stock intake. would probably gain a fair amount of power over the stocker]

a VH that could make 600 motor horses when i need it, and have decent low/off boost power is what im shooting for.

[1992Q45A]

I dream/lust of the VH M5 killa

[mtcookson]

whew.... too many different ideas to decide upon. lol

what's so nightmare-ish about the stock intake manifold?

[IvoryJ30t]

i hate the way the lower intake tubes "wrap" around the fuel rail, and obstruct the hoses [fuel, pcv]

also, id rather have a top feed rail.

in the manifold design i have, the manifold wouldnt extend over the valve covers. and the fuel rail would be laid out much different. top feed injectors, each rail fed from the rear, with the front of the rails "t"ed to an FPR. [swirl tank setup]

aside from externals, the motor work would be rods, pistons, head gasket, coatings, port work, and maybe different exhaust valves. 8.5-9:1 compression.

[mtcookson]

that sounds about where i would like my setup to be.

[450sxtc]

that sounds about like the manifold I'm building. Mine has the throttle body in the center of the motor facing the front of the car. I'm running top feed injectors with custom fuel rails made from summit fuel rail blanks. I'm also running the aeromotive 800 pump. The upper plenum is bowl shaped with equal length runners that split into at the base where it bolts to the heads. Can't wait to get it running.

[IvoryJ30t]

thats exactly what i have in mind. i have photoshop CS, but i cant draw for ****. maybe ill give it another shot and see if i can come up with a decent drawing.

RRE sells denso injector weld bungs. i would have the rails machined from blank stock. thats the least involved operation of this whole plan.

also, TMS pointed out that the VQ30DET has the same bore diameter as the VH, and come precoated with thermal barrier on the crowns and anti friction coating on the skirts.

that motor makes about 300 stock with 6 cylinders, so eight of them would be 400 hp, and a 50% increase in power is my 600 hp goal. i think they could take it. just have to have the rods made to match the pistons.

and since the pistons come precoated, i just need to do the heads. hopefully the stock exhaust valves will survive with the coating.

another cheap insurance policy is getting the crankshaft nitrided. im not sure if it comes case hardened or heat treated from the factory.

can anyone tell me if the cylinder bores are nikasil plated in the 90-96 motors?

[mtcookson]

so what are the benefits of the top feed injectors over the side feed? do they flow better?

[IvoryJ30t]

personally, i think there easier to deal with, its easier to make a custom rail for them.

and top feed injectors dont interrupt the flow of fuel thru the rail like side feeds do, and i think they are a better design. i just would rather have top feed injectors.

it makes the manifold easier to fab up.

[mtcookson]

ahh, i see. after looking around at injectors it seems those are the way to go as you can get higher output injectors with the top feed over the side feed.

[IvoryJ30t]

i have to run the numbers again to be sure, but 550cc injectors should be good to 600-650hp worth of fuel.

[IvoryJ30t]

yeah, 595cc's are good for 600hp at 43psi, a BSFC of .6, and an 80% duty cycle. that leaves a nice margin.

NOTICE*** corrected. i doubt there are 595cc injectors. i just corrected my calculation.

[mtcookson]

that's weird... according to another calculation i've seen on the net the 550's on a V8 should be good for 880 hp at 43 psi and something like 90% duty cycle.

550 / 5 = 110 (hp capability per injector)110 * 8 = 880 hp total handling

would the 10% difference in duty cycle make that much of a difference?

[IvoryJ30t]

it may have made the calculation with a BSFC of .5

that makes a world of difference. boosted motors run at a richer A/F ratio than N/A motors, and consume more fuel to make the same horsepower.

also, you should do the calculation with a duty cycle of 80%. it gives you more headroom, and your not stressing the injectors.

[IvoryJ30t]

http://www.rceng.com/technical.htm

i just reran the numbers, and i got mixed up in the above post. i would need 600 cc injectors for 600hp.

i would bump that to 660cc injectors to leave room for max boost.

on the calculation sheet, enter your target horsepower, and use the BSFC of 0.60, 8 injectors, a duty cycle of 0.80, and the fuel pressure is 43 psi.

thats leaving a nice margin. you could get away with less, but its not good to gamble with the fuel delivery.

[mtcookson]

ahh, i see. RC engineering seems to have a pretty good injector calculator. (bottom of page) http://www.rceng.com/technical.htm

Most of the injectors I've found that are a decent size are low impedence setup. Is that common or does this website just suck? lol

lol, just a second too late on my post for that link.

[IvoryJ30t]

haha. most performance injectors are low impedance. the waveform output from the ecu is different. its a peak and hold. the the voltage spikes to open the solenoid, and then drops and stabilizes until the injector closes. a high impedance injector uses a square wave.

usually you can make low impedance injectors work on a high impedance ECU by using resistor packs. the waveform sent by the ecu will be wrong, and i dont reccomend it.

im most likely going to have to find a top feed high impedance injector.

RC makes good ones.

[mtcookson]

but expensive... that's for sure. I think my Z uses a high impedence ecu with low impedence injectors stock. Its kind of weird but I'm pretty sure that's how its setup since it has resistors before the injectors. I'd like to find high impedence, high output injectors as well. Just have to search some more I guess.

[IvoryJ30t]

low impedance injectors usually come with resistor packs.

impedance has to do with the inductance and capacitance also.

i was just saying that it is possible to use low injectors with a high impedance ecu, but it wouldnt be correct.

i wouldnt have a problem finding injectors for this. i might even be able to get ones that will plug into the factory plugs, and not need new pigtail harnesses.

injectors will probably be like $100 a piece.

[mtcookson]

ahh, i see. i didn't know they came with them seperately.

[IvoryJ30t]

yeah, even on a stock setup, low impedance injectors come with resistors.

[450sxtc]

For those of you who like junkyard parts, here's an interesting bit.......in 1984 & 85 mazda made a version of the rx7 called a GSL-SE. It had a 13b 6 port in it and it ran low impedence 660cc injectors. They are top feed and if you can run down enough of them for a V-8, they would make a great set after being sent to rc or someone for a flow balancing job. I have 4 of them. Looking for 4 more, if anyone knows someone who has anyof these cars and you don't want the injectors out of it, then let me know please. [email protected]

[mtcookson]

Might contact John at J&H Racing in Bloomington, IN. I'm good friends with him. He specializes in Mazda rotary engines. More than likely he'd have some laying around. You can get his e-mail or phone number from http://www.jandhracing.com

[450sxtc]

cool thanx man

[mtcookson]

Someone on NissanX brought up a thought to me tonight. For a transmission, anyone ever thought of using the 350Z 6-speed? After looking for some a car-part.com they are actually priced about the same as the TTZ transmission, you get 1 more gear, and probably best of all these things have VERY LITTLE mileage. I was quite surprised. Also, since fabbing is required for the TT transmission more than likely the same amount of labor would go into the 350Z transmission to get it on.

Just a cool idea someone brought to my attention.

[maxnix]

With some of the the issues the 6MT guys are having on the G35 forums, I don't think I even would hook it up to a stock V8, let alone a modified one. A heavier duty unit would be safer.

[mtcookson]

ahh, so they are having some issues with those trannies? I was pretty worried about that since there aren't too many high powered Z's/G35's around due to the engine design (from what i understand).