N/a Modifications Explained

[simjim89]

would very much depend on the car. what most people think of when thinking about aero effeciency is the front of the car, however it is often the rear of the car that makes the biggest difference. for example, back in the late 80's and early 90's volvo racing cars were wagons as they were better aerodynamically than the sedans, despite having the same front end. a lot of cars actually get a big swirling vortex at the rear of them which creates a low pressure area behind them. this actually sucks them backwards a bit. anyone who has driven a station wagon or hatchback in the rain will see how much spray from the tyres ends up on the rear window. if you look at the back of a lot of wagons you will see a little spoiler type thing that directs air downwards (my vt wagon has one). this helps to reduce the vortex, or at least move it further back from the car to reduce its affect.

this vortex does have 1 advantage though. if you happen to be able to get behind a truck on a bike then you can really get some speed up without much effort.

Drag coefficant is the technical name isent it ? and when altering the any shocks or going to coil overs shouldnt roll/sway bars be considerd also ?

[mad082]

In short no, the car will run yes, but wont net any real gains without a decent exhaust at the very least.

Also Cams for turbo engines differ greatly to NA engines. So while you can have a 260deg 8.8mm lift cam for a turbo engine and an NA engine, things like the LSA and the ramp rate of the cam lobe are quite different.

So while the Poncams etc would work ok, there would be better results had by getting a custom set done specificly for your NA engine.

what cams work in NA and turbo versions can vary greatly. for example, natro sr20 cams are actually an upgrade turbo sr20's.

Part: Splitfire , super spark . yellow jacket ..... coil pack

why : standard coil packs burn out ... they work in extremely hot conditions and with really high ammounts of electricity

burn out means eventual engine light and horrid missfire usualy in the conditions late at night in the rain and no were near a work shop becasue the spark is not going were it should

results : desputeable gain but more importantly relyability and not having to baby your car home couffing farting spluttering and carrying on

2 things, engine light only comes on in the r34 and the actual performance gains from new coils is technically zero, since all you are doing is restoring them back to their original performance.

[PM-R33]

Drag coefficant is the technical name isent it ? and when altering the any shocks or going to coil overs shouldnt roll/sway bars be considerd also ?

You are trying to cover like 10 different topics in one thread. Perhaps search in the suspension section if you want answers to questions like that.

I understand what you are trying to do, however it really is pointless and isn't going to be used as a reference point in any way.

If you wanted to do it properly (and I suggest doing a LOT more research first) write out everything in a word document and then make one large post. Then PM a moderator in the NA section and ask for it to be a sticky.

[zebra]

Drag coefficant is the technical name isent it ? and when altering the any shocks or going to coil overs shouldnt roll/sway bars be considerd also ?

Yes they should be matched, Risking on these forums is the guru on all things handling, he recomends +2mm over the standard Anti-Roll bar sizes on Sylines.

Spring weights and shock dampings depends on many things such as CoG weight split, intended use etc.

So very hard to give a good idea on what to get.

[zebra]

what cams work in NA and turbo versions can vary greatly. for example, natro sr20 cams are actually an upgrade turbo sr20's.

Indeed, Supercharged Ls1's (and I mean properly superchaged...not those ghey Votech/powerdyne things) Love big radical NA type race cams over the more traditional "blower grinds"

[mad082]

Drag coefficant is the technical name isent it ? and when altering the any shocks or going to coil overs shouldnt roll/sway bars be considerd also ?

technically many things should be considered when making suspension changes. even just things like wheel alignment settings. for everyday use picking off the shelf items is just fine for a small increase in handling and a better look. if you are going to track the car and want every last tenth you can then you would need to start really looking at every aspect of suspension and matching up all the items to suit each other.

[zebra]

You are trying to cover like 10 different topics in one thread. Perhaps search in the suspension section if you want answers to questions like that.

I understand what you are trying to do, however it really is pointless and isn't going to be used as a reference point in any way.

If you wanted to do it properly (and I suggest doing a LOT more research first) write out everything in a word document and then make one large post. Then PM a moderator in the NA section and ask for it to be a sticky.

I agree here, this topic should be limited to Engine work

[mad082]

ok i think i've done enough helpful posts for one day, so i'm going to go find someone to make fun of.....

[simjim89]

You are trying to cover like 10 different topics in one thread. Perhaps search in the suspension section if you want answers to questions like that.

I understand what you are trying to do, however it really is pointless and isn't going to be used as a reference point in any way.

If you wanted to do it properly (and I suggest doing a LOT more research first) write out everything in a word document and then make one large post. Then PM a moderator in the NA section and ask for it to be a sticky.

bannanas peel left to right

[Gerg_R31]

Addition to porting think of it like a macca's thick shake, the standard straws you get with the cokes are useless with the thickshakes, but if you ask for their purple ones they serve with the smoothies, much better, but if you decide to go bigger and use for example a vacuum hose you'd just make a mess of things and will eventually be less sucessful then the first option, aka bigger ports is not always better. Also, the "polishing" of the ports is quite pointless, if the ports are too smooth fuel will stick to them, and in that few minutes while its running rich while its being tunned the unburnt fuel will cling to the exhaust ports.

Valve Seats the RB motors all come out with the 3 angle seats from factory (30° crown 45° seat and 70° throat) the best angles for flow is a 4-5 angle on the intake with a 1mm 45° valve seat, and a radius on exhaust with a 1.5mm 45° exhaust seat. With addition the intake valve should have a 30° back cut on the port side of the valve for a better flow

Addition to cams I have found with my n/a RB26 head on my RB30 block, doing the maths and calculations, as a rough guide the exhaust cam should have 10 degrees more duration at 0.050" lift

Valve Springs

I've read alot of posts where people try to get, or suggest the stiffest/ heaviest springs possible, this is not going to help. If they are too stiff they will chew out the cam lobes and pull the valves into the seats, end result need to buy new cams and valves and have new seat inserts fitted. If bigger lift cams are used and the springs dont suit, you will end up with "valve bounce"

The correct method is to find the springs to suit the cams

To find out if the springs suit,

Seat pressure measure the installed height of the valve (spring base to under retainer, or spring base to top of retainer) use the spring base washer, spring (and retainer if measured with one) put it in a spring tester and pull it down to installed height, the seat pressure should be 70-90 pound on a N/A RB motor (add 10-15 per 14psi/1 bar of boost for forced induction as a rough guide)

Springs to suit cam with the spring in the spring tester, find the measurement of the spring at coil bind (fully closed) then simple maths, coil bind - installed height - 0.100" = same or more then the cam lift. Less then the cam lift, you'd get valve bounce

Blue Printing is the process of making every cylinder working exactly the same as the others, This is acheived by all the combustion chambers the exact same volume, ports all flowing exactly the same, all the con rod little end big ends and total weights all the same, all the pistons weighing the same, crank flywheel and pressure plate balancing, weight matching rockers in some applications, Pistons are of a better quality these days where the manufacturers promise each to be the same size, where as the old days all the pistons would vary and the bores would be "blue printed" to suit each individual piston

Grinding RB25/26 Heads People have stated that for every 0.010" ground off any head will remove 1 cc. Some cases this is true but not in every case as the combustion chambers eventually tapper. From my experience and measuring, the first 0.020" ground off the RB25/26s will remove 2 CC's Grinding 0.080" off will remove 12.5 CC's

Compression Ratios this is quite often assumed and guessed and where someone may think that they might have 12:1 they might only have 9.5:1

The formula to work out the static compression ratio

Swept Volume

Bore x Bore = Answer1

Answer1 ÷ 4 = Answer2

Answer2 x π (3.142) x stroke = Answer3

Answer3 ÷ 1000 = Swept Volume ( SV )

Compression Volume

Head CC

Piston dome/ dish volume

Deck height (if 0 deck height leave out)

Bore x Bore = Answer1

Answer1 ÷ 4 = Answer2

Answer2 x π (3.142) x block deck to piston crown measurement = Answer3

Answer3 ÷ 1000 = deck height volume

Gasket

Gasket Bore x Gasket Bore = Answer1

Answer1 ÷ 4 = Answer2

Answer2 x π (3.142) x Gasket thickness = Answer3

Answer3 ÷ 1000 = Gasket volume

The Maths

Head CC + gasket Volume + Piston dish Volume or - Piston dome volume + deck height or - if piston is above the deck = CV

SV + CV + Answer

Answer ÷ CV = Compression ratio

thats all i can think of off the top of my head

[KezR33]

Part: Full exhaust - extractors, 2.5" manrel bent system with high flow cat.

Why: Wanted moar powah.

Result: Waste of money. The gain is there, but its hardly noticeable. Wish I'd saved my money for a turbo.

Part: 2-way TRD LSD

Why: Open diff blows, makes the car highly unpredictable and difficult to learn in.

Result: Best thing I've ever done. Car is infinitely more fun to drive and I've learned a lot about car control.

[mad082]

Part: Full exhaust - extractors, 2.5" manrel bent system with high flow cat.

Why: Wanted moar powah.

Result: Waste of money. The gain is there, but its hardly noticeable. Wish I'd saved my money for a turbo.

Part: 2-way TRD LSD

Why: Open diff blows, makes the car highly unpredictable and difficult to learn in.

Result: Best thing I've ever done. Car is infinitely more fun to drive and I've learned a lot about car control.

you just failed at the internet

[Gerg_R31]

Addition to cams; with the RB30DE when selecting cams if the cams are rated i.e 3000-7000rpms on the rb25/26 head, with the RB30DE the same cams would be more 2000-6000rpms

[Gerg_R31]

What? minimum piston to valve clearance should be 0.080" on the intake exhaust usually too far away to be a big issue in the rb heads

Why? High revs and thermal expansion internal parts will expand, too little clearance = damaged pistons and/or valves

How to check piston to valve clearance

cover piston in clay/ play-do about 1/2 inch thick, put head gasket on, bolt down head, set timing, turn crank twice pull head off and with vernie calipers, measure from where the valve stopped to the piston top, side of the dome, top of the dome

with mine, I had 0 deck height, 10cc pistons, 1.2mm head gasket, and 0.080" ground off the head, intake was 0.130" and exhaust was 0.250" with a 10.8mm lift cam and 10.5:1 compression

[simjim89]

Thanks greg ... and how did that end up working out ? bettter feeling result power ?

[Gerg_R31]

Thanks greg ... and how did that end up working out ? bettter feeling result power ?

might want to re-word that in detail so i can answer that

if your wondering what my rb30de made, i have bothered checking, havent finished the ramtube manifold yet, tough im more interested in response then dyno numbers

[GTR-N1]

You are trying to cover like 10 different topics in one thread. Perhaps search in the suspension section if you want answers to questions like that.

I understand what you are trying to do, however it really is pointless and isn't going to be used as a reference point in any way.

If you wanted to do it properly (and I suggest doing a LOT more research first) write out everything in a word document and then make one large post. Then PM a moderator in the NA section and ask for it to be a sticky.

I will agree with Phil on this.

There has been no limit on the aspect of "budget"

And so, with no limit on budget, I'll try to contribute to this thread from yet another different angle.

Weight:- To compete against the BR-Z or 86GT on weight and with heaps of moolah, perhaps I would...

* replace the s/steel exhaust with a Kaki Mega N1 Titanium

* replace existing glass with a thinner gauge like what's on an M3 CSL

* replace steel guards and bonnet with aluminium and c/f

* replace existing strut brace with Nismo titanium

* further reduce unsprung weight by getting light Enkei rims

* get rid of mats and soundproofing

* remove a/c

* remove speakers and head unit

* remove rear wiper

* did you know that child restraint brackets weigh more than a Kg?

* and I haven't enquiried yet how much you weigh, to help power/wt

[MRIRAQ]

bump,

[Captain Natro]

bump,

What for!?

[MBS206]

What for!?

Because retard.