Engine Rebuild Options

[No Crust Racing]

Going to get the current motor through this season to stay in my class and do a swap end of year, going from CA to SR, have already started dissembling the SR for a basic forged rebuild - this is not an all out no expense spared deal but "sensible" with some niceties . Dedicate track (grip) car so not after dyno queen performance. 

The goal is to have the headroom for 300-320rwkw on e85 and whatever it makes on 98. I realise this will mean a box swap as well. Car is highport/redtop so no VCT. Expecting bore to be 86 or 86.5mm. 

Plan was to base it off the Spool rebuild kit (CP pistons, not Ross) and add ARP main studs to that kit, plus new gaskets,hoses, fresh oem water/oil pump/timing kit/balancer, basic valve spring/cam upgrade and a mild port/cleanup etc etc.

Things I'm unsure of. 

• 8.5 or 9:1 compression? Higher = better spool for larger turbo, but more prone to knock or not an issue on e85 and just run less timing?
• How big to go with Cams, 256-264 range? Will stick with hydraulic lifters but will buy new ones and add rocker are stoppers, plus I don't bounce it off the limiter.  
• Worth bothering with something like this intake manifold? Mazworks claim no lose of response with theirs, awaiting info on this cheaper version.  https://otakugarage.com.au/product/otaku-garage-billet-intake-manifold-forward-facing-plenum-sr20det-s13-s14-s15-180sx-240sx/
• Can either add wastegate port to stock manifold and give it a basic tidy up or hunt around for second hand 6boost etc if the cost is worth it. Can also ebay something like this - https://www.ebay.com.au/itm/Twin-Scroll-Turbo-Manifold-T3-SCHEDULE40-FOR-Silvia-240SX-S13-S14-S15-SR20DET/192490055785?hash=item2cd14d2869:g:0j0AAOSwnONZBEhW
• What turbo? Have looked at GTX3067, but I'm not convinced it will get to 300, it might with better intake manifold, gated, etc? Looked at GTX3071, EFR 6758/7163 (bonus of seemingly being able to make the power on IWG setup and does come in T25 config plus everyone ravs about the transient but very expensive. Kinugawa version GTX seems to be in the middle, new for 1400 or so, but then why not Hypergear etc?

I ask here as Silvia forums is dead and asking on the Facebook groups is just painful having to deal with the morons. 

 

[GTSBoy]

Defo 9:1.  Even higher if possible, with E85.

Cams keep gentle if you're not going to replace all that weak as shit SR gear on top of the motor.

Cheapskate the ex manifold.  Put the money saved towards some head work.  A little attention in the ports will be worth more than bigger cams, better manifold, etc.

[admS15]

If the plan is to run constantly on e85 9.5 or even 10:1. Will help off boost and lower rpm dramatically considering no vct and on e85 knock wont be an issue at all. Will need conservative timing and boost on 98 though.

[No Crust Racing]

22 minutes ago, GTSBoy said:

Defo 9:1.  Even higher if possible, with E85.

Cams keep gentle if you're not going to replace all that weak as shit SR gear on top of the motor.

Cheapskate the ex manifold.  Put the money saved towards some head work.  A little attention in the ports will be worth more than bigger cams, better manifold, etc.

Depends on what needs replacing. It'll get stoppers, it'll get new lifters and better springs. I would've assumed the retainers were fine and the valves themselves have no impact on relaibility? Are you talking solid conversion? IF so I'll pass purely due to maintenance. 

Cams don't seem to need to be as aggressive on SRs to flow power, maybe because they have so much more lift compared to CA/RB26? 

Spool list 8.5 (stock I think?) 9.0 and 11.0:1 as options.

17 minutes ago, admS15 said:

If the plan is to run constantly on e85 9.5 or even 10:1. Will help off boost and lower rpm dramatically considering no vct and on e85 knock wont be an issue at all. Will need conservative timing and boost on 98 though.

As above Spool list 8.5 (stock I think?) 9.0 and 11.0:1 as options. 11:1 seems crazy. I'ms sure I could get something custom, but this is a mid tier build, so maybe 9:1 is the answer. 

[admS15]

Yeah out of those options 9.0 would be the go.

[Leroy Peterson]

IMO (from FWD SR experience):

dont bother with intake manifold. What do you plan to gain? plenty of people making big numbers and do fine with stock intake. Just adds extra work/complications with throttle + idle air + OEM equipment access/clearance.

mild turbo cams, or even give OEM a go and see how it handles, can always upgrade later. Put effort/money into valvetrain a bit for 300kw. springs etc.

No VCT and no VE, so would be worth port matching intake and exhaust.

GTX30 gen2 should have no issues getting to 300kw. Most people say the GTX dont really wake-up until 20+psi.

Top feed injector conversion? might be cheaper/easier to source ideal injectors that way.

Just make sure cooling/oil is up to scratch. No point in power without reliability.

[No Crust Racing]

Mazworks show very good gains from their intake manifold, the idea being that those supporting parts can help a smaller turbo reach the goal, like I did I my GT-R. 

Plus highport looks aids and puts all the hoses/sensors under the manifold in a shit spot. 

What do you suggest on valvetrain? As stated it will get springs and rocker arm stoppers with fresh lifters. 

When I say GTX I just mean Kinugawa variety, not sure if they are Gen2 or not, unless a second hand Gen 2 comes up. And if so, 67 or 71? 

Injector conversion is just a fuel rail isn't it? 

Radiator will be upgraded, I already have an oil cooler setup in the car with thermostat and relocator, I can just change the sandwich plate and keep using it - though I may go for a bigger core. I'm also looking at replacing factory bonnet with vented and it currently runs radiator air guide and factory clutch/fan setup which will stay as they work. 

 

 

 

 

 

 

[No Crust Racing]

Doing more reading of course and hearing some interesting things. 

• Avoid cometic head gaskets?
• Consider wedges between bores in the cooling slits to avoid deformation (seems extreme for a mild build)
• Run a "modified" S15 pickup instead of S13, though mine appears the same as the one that Taarks sells as being the "updated" version. 
• Avoid spool rods?
• S14 girdle instead, required line bore I'd guess.

??

[admS15]

Yes, avoid cometic hg on SR's. Mine lasted a few years and then started to leak from combustion chamber into water jackets in a few spots and that was with arp 2000 head studs doing the clamping. I replaced it with a Nitto. Was pricey but meant to be the goods. I also hear good things about cosworth hg's and are a bit cheaper i believe.

[No Crust Racing]

Good to know, that's one issue avoided hopefully. 

[No Crust Racing]

Thoughts on parts from Goleby's?

Their timing chain kit is half the prie of OEM, includes cam gears also. 

Their lifters, Nason Engine parts? $100 for a full set versus $800 or so for OEM. 

I will go with Ross race series or OEM for balancer, but some of this other stuff, is there much in it quality wise? 

Looking at either BC or PErformance Springs, both around the same price.

Worth looking at tomei/other rocker arms? 

 

 

 

[No Crust Racing]

Also thoughts on Solid heads? Some parts I'm being offered includes a head. 

"tomei solid head, brand new rocker arms, tomei ras, tomei cam gears and 260 cams
supertech dual valve springs, ti retainers, valve stem seals and 1mm oversized in/ex valves and ported and polished to suit"

I like everything except the solid component as I worry about the maintance ongoing, but it's done only 2 dyno runs an is and is very cheap. 

Could swap out the cams and lifters for hydraulic? Or just learn how to check/adjust clearances on the reg? 

 

 

 

[Leroy Peterson]

Don't bother with solid lifters... You're not going big cam and you shouldnt be revving the shit out of it.

 

If you really want that peak 300kw, then go the bigger GTX30 when IMO the latest GTX28 will be enough (or if it doesn't make 300, will be a much better suited turbo).

 

+1 to cos worth headgasket

 

+1 to BC automotive springs

 

In regards to valve train... I think usually RWD guys go for springs (sometimes retainers), Rocker arm stoppers (but is often contested by people saying it causes issues), cam gears + cams, removal of squish pads (I think) and some go valve stem seals (not sure why, get machine shop to check the head over).

 

I don't know why you're replacing rockers unless they're worn. Don't bother with Tomei/Jun/Naprec valve train stuff, seriously expensive and shouldn't be required for a mild build.

 

Also: consider what other mods the mazworx motor had when doing the plenum results.

I think PITA stuff under the plenum is unavoidable unless you're stripping the engine bay and redoing everything.

[No Crust Racing]

It's only that the head is complete with all that gear in it already.

Seemed like an odd combo, he's got a stroker kit there with that head, not sure on the crank brand, only that it's 92mm, billet, knife edged. Anything i could find was 91mm. Custom JE pistons, so it could be a very fun combo with a 30 frame on it. 

That whole collection of parts was very competitively priced. 

[BakemonoRicer]

You can take my gt3071r for $1550 now that ive gone a big 7670...

type in rezlo s14 to youtube he is running small 256 cams and putting out big numbers.

SR's do not need big cams!

 

[No Crust Racing]

Yeah, no.

[BakemonoRicer]

allow 12k to build a head if you do it from scratch pal

 

[No Crust Racing]

Odd the email i got for this post update had 10k in it? Missed a receipt did you lol

Not looking to build a baller head, not need for my purpose.  

[Leroy Peterson]

$12k on the head?? Is this the Naprec one?

Could get mazworx built VE with conversion kit for less.

 

I spent less on my whole GTiR motor and could make 300 if the gearbox/driveshafts/tyres could handle it...

 

 

[SRS13]

If the solid head is from a reputable seller, grab it. Then take it and have it serviced for peace of mind. To build a head like that will cost a fair bit (price each component individually and then add labour for asembly and port work)