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J_Rho
05-30-2005, 11:23 PM
Hello all,
First post here, been reading, reading, reading for the past few weeks, researching my setup-to-be. Great info here.

Background:
Car is a 1968 Datsun 510. It is going to be used exclusively for SCCA Solo2 autocross purposes in the Street Modified category. The car is very lightweight and will run ridiculously large and sticky tires that will take all the power I can throw at them. Being an autocross car, good throttle response and squirt out of the corners in the middle RPM range is more important than huge top-end power. Peak power requirement is 350+whp, with as broad a torque curve as possible.

Plan is as follows:
S15 SR20DET
Garrett GT2871R .64 A/R
Peakboost or similar top-mount (needed for fitment in 510)
Walbro 255 lph fuel pump
740cc injectors
FMIC
rocker arm stoppers/upgraded valvesprings (raised redline)
lightweight flywheel/upgraded clutch&pp

So...I'm interested for feedback on this plan, and on any ways I can get a broader powerband. Obviously it'll need to be well tuned once put together. The car will be trailered around pretty much everywhere, so I'll plan to run it on race gas most of the time, if that helps. I've looked at intake manifolds, cams, or a head gasket to lower compression, but I'm not sure if any of them will help the low end and midrange. Any power gained above 6000rpm won't help me if it brings losses in the 3500-5000 range.

The 6 speed that comes with the S15 swap packages has a better second gear for my purposes. Besides initial cost, are there any downsides to the 6 speed, like less strength? Also, does the S15's VVT deal help to give the car a bit more oomph before boost comes in? Based on my reseach with the .64 GT2871R, boost should be in around 3750, and while I plan to spend very little time below 3500rpm, it might happen occasionally. I could just as easily run an S13 or S14 5 speed, and just re-gear the rear end, if there are no advantages to the S15.

I had considered the Disco Potato for its great response but its ultimate hp potential is a bit below what I'm looking for.

Lastly, if anyone can recommend a reasonable "one stop shop" for all the stuff I'm looking for, that would be helpful as well.

Thanks in advance!

killjoy
05-31-2005, 07:53 AM
Are you gonna upgrade springs without cams? I don't even think I would bother with the head at all unless you will switch cams but you don't want to lose low and midrange so i doubt you will switch cams anyways. If you run the PB manny you will get a topmount t2 right? Otherwise the t3 would raise your spool time.

Lastly why bother with a s15 engine? Waste of money if you are upgrading turbo imho.

J_Rho
05-31-2005, 10:33 AM
The reasoning behind upgrading valve springs was to improve reliability in the 7000-7500rpm range, where the car will spend a bit of time. In autocross it's often better to "bounce off the rev limiter" in second gear than it is to shift to third, since doing so can be tricky and possibly upset the car.

Yes, I would do the T2 flange turbo with matching manifold. Sorry, should have mentioned that previously.

I haven't been able to find any dyno charts of S15 motors with similar mods. My hope was that the VVT system would improve torque below the rpm where boost comes in. If this is not the case, then indeed, the S15 would appear as an unnecessarily more expensive option.

killjoy
05-31-2005, 11:27 AM
I would guess that it would not be worth it for the little you might gain. But I have never used a vvt nissan so maybe i am wrong. But i would make a serious wager that I am not:)

_Def_
05-31-2005, 02:48 PM
Go with some HKS 256 Step 1's or something like that. I doubt you'd lose anything in the midrange with them, and you'll pick up more power on the top end which does matter. The stock cams are pitiful 240/240(at least on S13's), and they don't exactly give you much power over a little bit hotter cam down low. Something like 272's will take away a bit of low end, but not something mild like 256's.

steve shadows
05-31-2005, 03:05 PM
have you ever driven a 510 with that much hp before? do you know what your getting yourself into? traction will be fun.

J_Rho
05-31-2005, 03:35 PM
have you ever driven a 510 with that much hp before? do you know what your getting yourself into? traction will be fun.

Have not dealt with that much power in a 510, but I have autocrossed cars with that much power, or substantially more. The 510 is getting a ridiculous flare treatment and 12" wide rear wheels, so it should be able to handle the output.

I had considered the 256 HKS cams, I'll look at them again. Since more lift doesn't hurt midrange too bad, are there other options (Tomei, Jun, etc.) that offer more lift but keep a reasonable duration?

Cr0usEEE
05-31-2005, 05:57 PM
have fun getting that rear suspension to "stick" sometimes i think the 510 wagon would be a better autox platform due to the solid rear axle....and more room to add balast.

but for what your talking about....

just go with a stockish s13 or s14 engine. more than enough torque for your needs, cheaper, 5 speed is the same as oem 240sx 5 speed (for when it pops). plus you could just order an engine set since if your going this hardcore you might as well run a full standalone engine management system.

no matter what...if your going SM be prepared. Mark Daddio is still running his 400 horse EVO RS and Bob Tunnel/Vic Sias both have the 95 m3 lightweights that are FAST.

also are you going to be running a 6pt roll bar?? unless you have a lower milage car im guessing it has lost some of its rigidity...just something to think about

J_Rho
05-31-2005, 06:15 PM
Yeah, it's going to take big spring rates and some work on the semi-trailing arms to get the camber stabilized in the rear. I'm planning on running 335/35-17's, which should help a bit, and the car should end up with about a 45/55 front/rear weight distribution, great for putting power down.

Vic is definitely the guy with the target on his back. The 510 looks a bit better on paper - over 200lbs. lighter, better weight distribution (since I'll have to add 200+ lbs. ballast), and even with the big tires, will be about 2" narrower.

Daddio is going to be very very tough, but he's going to have a hard time getting that car light enough - it's probably going to end up quite a bit heavier than Vic's car.

I have recent dyno plots of Vic's car, Daddio's car, and Dennis Grant's Eclipse, and collected their tire and gearing data to form thrust vs. speed graphs for each, to see how the SM 510 compares.

While in boost, it compares quite favorably. http://forums.freshalloy.com/images/graemlins/laugh.gif With short gears it gets to boost quickly, but is hampered by the 7000rpm redline. With stock or mild cams and hefty valvesprings like the Ferrea, what sort of redline do you think would be reasonable (and reliable)? Granted, the car will start running out of breath in the upper rpm ranges, but in autocross that is almost always favored to shifting. Raising the redline to 7500 or 7750 would help a ton!

Dave562
05-31-2005, 10:07 PM
Your power goals might be a little bit high. The 510 is a really light car. Before you go and throw a bunch of money where you might not need to, see what you can do with the SR20DET, a T28 turbo, flywheel, clutch and about 14psi. That should put you in the 280-300hp range, which is a ridiculous amount of power in a car that light. I think that you're on the right track with upgrading the head with valve springs and rocker arm stoppers. You don't want things flying apart at 7500+ RPM.

J_Rho
05-31-2005, 10:42 PM
True, the car is light, but in order to compete legally in Street Modified with a turbo motor, it'll have to weigh at least 2400 pounds, which is getting into "middleweight" territory. Depending on the car's unballasted weight, I might try to run it against the RX7s and Corvettes of SM2, where it would only have to weigh 2100! http://forums.freshalloy.com/images/graemlins/smile.gif

My competitors' vehicles are capable of sustaining >1g acceleration through most of second gear. Based on my planned tires and gear ratios, I need to be making 280 ft-lbs. of torque to produce that level of forward thrust. So my goal is to make that much torque over as wide an rpm band as possible (without utterly killing pre-boost torque), which ends up being 350hp just past 6500rpm. If it could hold that torque level all the way to 7500rpm (I know, not likely), that'd be 400hp! http://forums.freshalloy.com/images/graemlins/shocked.gif

I think the GT28RS would probably be just about as fast, but I think the extra top-end potential the GT2871R gives will make it a bit more exciting to drive.

Dave562
05-31-2005, 11:15 PM
If you are worried about torque, why don't you go with a KA24DET? You can make the torque levels you want at much lower boost levels. I think I already know the answer, because personally I wouldn't want to take a KA-T on a road course for extended periods of boost driven, high RPM racing, but I have to at least throw the suggestion out there.

J_Rho
05-31-2005, 11:53 PM
Indeed, the extra displacement of the KA is appealing, and I'm allowed to go all the way to 3.0 turbocharged before I have to add more weight. (For those of you thinking of a single or twin-turbo'd V6, the reason I didn't want to go that route was because of the extra weight involved, much of it over the nose of the little 510. Making room for the motor and all the plumbing would be a nightmare, though it has been done before)

I want to make a reliable 350whp, and the SR20DET seems like the best way to get there. The KA can get there too, but it would take custom rods and pistons for me to feel comfortable about it holding together, and that route is ultimately more expensive. I've also looked at the stroker kits for the SR but they're simply out of budget, at least at this time.

And yes, I do plan to occasionally track the car at some of the west coast tracks, and maybe drag it every once in a while.

And just to throw out another question, has anybody had good luck/gains with the JWT race-prepped cylinder head? They're here in San Diego, but I'd like to hear some good results before considering it. Search turned up nothing on their heads, just their ECUs and C1 cams...

Thanks again for this great resource! http://forums.freshalloy.com/images/graemlins/cool.gif

TheRiotHero
06-01-2005, 03:42 AM
dunno man, i hate to see it as im an SR guy myself but i think the best course of action would be KA24DE-T.

price.

KA = 0 - 200 dollars
wiseco 9:1 pistons - 550
new bearings, machining, badass newness - 600 top end.
custom intake manifold via ME http://forums.freshalloy.com/images/graemlins/laugh.gif - 450
full race style exhaust manifold and waste gate - 1200-1400
GT2871R .63 a/r T3 housing 4 bolt discharge - 1200
Crower V3 cams - 550
minor headwork and cometic gasket- 400
740 injectors - 500
used electromive tec3 or tec2 or any other GOOD standalone. - 500 - 1200

thats 5650 minus engine management, HIIIIGH end.
and itll be more responsive and torquey then you could possibly want and itll do easily 350whp reliably.

now lets check out S15 setup

S15 front clip - 3800-4300 http://forums.freshalloy.com/images/graemlins/blush.gif
fullrace manifold - 1200
wastegate - 400
(geez are we at 5 grand already? crap it doesnt even run yet!)
GT2871R-1200
injectors-550
headgasket - 110-230
cams- 430
springs,retainer, splid pivot kit - 800
aem EMS - 2000


the list goes on. cost gets way up there.

KA-T is better for your needs, you need instant torque and thats what a KA does best, not to mention, youll eb getting a 100% fresh motor for the season. obviously the costs are vague, theres alot of nickel and dime on both. probably looking at around 8 grand total for the KA, and probably about 10-12k for the S15 motor, and youd still have less power and torque then the KA.

J_Rho
06-01-2005, 12:00 PM
I'll look into the KAs a bit more, but I'm pretty sure the SR is a better choice for me at this point. Seems like there are tons of parts and options for the SRs at the moment, whereas turbo KAs have a much smaller following. I'm not looking to pioneer anything, I just want to go with a known-good, proven, reliable setup, and not have to worry about it.

I've pretty much been talked out of the S15, and will likely be going with an S13 or S14. So even if everything "outside" the motor (engine management, manifolds, turbo, etc.) cost the same between the two options (KA24DE-T, SR20DET), I figure a stock-ish S13 costs less than a KA24 + rods, pistons, etc., especially when you consider assembly costs.

Nevertheless, I'll look at some well-done turbo'd KA's to see what people have gotten out of them.

_Def_
06-01-2005, 12:46 PM
There's no reason to go with an S15 engine for what you want. VTC isn't going to knock your socks off, and the head doesn't flow as well as the earlier redtop head. Plus, since you want to rev, the S13 Redtop engines have a 7500 RPM stock redline. Just toss some slightly stiffer valve springs in there, RAS and some mild cams and your valvetrain is done. I have heard of people taking Redtops to 8000 RPM with stiffer valve springs, but I'm not sure how wise that is. You could maybe push it to 7800 RPM since I know how much autox lends itself to riding out 2nd gear for that split second longer.

I think your goals are pretty solid, and I'd definitely stick with the SR. The lighter engine weight just means you can move more weight to the rear of the car, which is where you definitely need it for autox.

What kind of diff are you going to go with? I think putting down the power will definitely be your biggest problem. Can you change suspension geometry at all? The E36 M3's have a really nice rear suspension that's very similar to the Z32/S13/S14 etc. suspension. It has great camber curves, and pretty good bumpsteer characteristics bone stock.

Vic Sais's M3 is pretty sick now a days though, with his TEC3 tuned S54 engine(3.2L 333bhp stock E46 M3 engine). Last I hear he was putting out over 300rwhp, but then again, it's still a 3.2L engine so the torque isn't all that crazy. Short gearing and a high redline make up for that quite a bit though.


As for rubber, do you really need 12" wide wheels? Wider tires do offer a small bit more grip, but if you can never get heat into them then I think you'd be better off with a narrower tire/wheel combo. This will also keep down unsprung/rotational weight. I'd think a 10" wide wheel would be more than enough for a car like that for conepacking. I run a 10" wide wheel with 275 street tires out back and I can barely get them up to temp in a 20-25 min HPDE session with my ~2560lb S13. Parking lot driving makes it even harder to get the tires up to temp in a reasonable amount of time.



It sounds like a neat project, and I think your success or failure will be dictated by your attention to the details. If it's easy to drive fast, then you have a chance according to the specs. If it's a PITA to handle at the limit due to the old suspension design and loads of power... then I'd say you'll definitely have your work cut out for you.

J_Rho
06-01-2005, 02:34 PM
Thanks for the input Def. Especially the bit about the earlier motors having a higher redline, I'll definitely look to finding a low-mileage S13 now.

The diff plan is to use a Quaife-equipped R200. From what I've heard it should be able to handle this power level, and gear ratios are plentiful. My installer buddy is familiar with what needs to be done to get the R200 to work in a 510 or early Z car, having done it before.

Here's a page that has dyno plots of some of my competitors:
http://www.siastuning.com/SMspecs.htm

Granted, a few of those are outdated - McKee and Thomason for certain, and I'm sure Sias has added power since then. Still, I used that data, along with their tire sizes and gear ratios to build a speed vs. thrust spreadsheet for their cars and the 510 with a few different rear ends. Here it is, (still a work in progress):
http://user.gofastlab.com/jzr/510accelerations.xls

For the 510, I used a dyno chart I found of a guy on this board with a similar build - SR20DET w/ .64 A/R T25 GT2871R, mild HKS cams, and a few other tweaks. I had to extrapolate the curve out to 7750 rpm though, so that part might be off. As you can see I'm also trying to decide which final drive ratio to use, right now it's between the 4.36 and the 4.63.

The one thing I note from this exercise is that the fastest autocross cars tend to have the broadest powerbands, which is what I'm hoping to acheive with this motor. If I could have it pull hard from 3750 to 7750, that would be superb, and I think make it easier to drive.

The pros to going with wider wheels are many:
-wider tires, more lateral and longitudinal grip
-wider track, car less likely to roll over
-running Corvette sizes ensures tire availability
-intimidating to run the same sizes as Vic on a 200+lb. lighter car

And the single con, the car is wider. It is presently 60" wide up front, 61" wide rear with 14x6 wheels and skinny little 195 Falkens - afterwards it'll be about 72" wide up front, and 70-71" wide in the rear, since I still have some room to go inboard back there. It'll still be narrower than Vic's car by about 2". Plus I've heard many stories of 510s on their roofs, so I think I can live with the width. http://forums.freshalloy.com/images/graemlins/smile.gif

In my experience the Kumho V710s work best at just above room temperature, so I'm not too worried about the heat issue. Plus, with the way I drive, they tend to get warm quickly... http://forums.freshalloy.com/images/graemlins/smile.gif

The suspension geometry is yet another challenge. Fortunately I can do whatever I want, as long as the factory mounting points are retained. My plan in the rear is to have the semi-trailing arms notched for inboard wheel/tire clearance, and have the spherical bearings installed at the inner pivot points in such a way as to de-camber the rear. Obviously though, the yucky rear suspension is going to be something to try to make the best of.

asad
06-01-2005, 02:56 PM
Hmm...is it against the rules to build a (fixed) subframe that attaches to the stock suspension mounting points, and then build a new suspension off of that? It would probably add some weight, but if it's legal it might just be worth the effort.

Asad

TheRiotHero
06-01-2005, 03:04 PM
you dont need aftermarket rods for a KA< theyre strong as hell stock, if you really wanted to do a s14 motor email me.

knightgarage@hotmail.com

i have something you might be interested in.

J_Rho
06-01-2005, 04:53 PM
Unfortunately I can't really do anything to the subframe, and all moving parts still have to pivot off their original locations. It's a good thought though!

_Def_
06-01-2005, 06:30 PM
Hopefully you can get those meats up to temp then, and I hear you about the tire size problem. That's why I eventually had to go with 17's versus the 16's I wanted as there just weren't any good tires in a variety of 16" sizes(street tires, will probably go 16" for R-comps).

I think you'll be good to go with an S13 Redtop and that setup. I think forged pistons are allowed in SM, so you might want to drop in a set while you have the engine out. You could also go with a 9.0:1 CR since the car could feasibly have a steady diet of at least some race gas.

Best of luck to you, it'd be nice to see a Nissan start whooping up in SM - even though my daily beater is an E36 M3. So it's easy to cheer either way... http://forums.freshalloy.com/images/graemlins/grin.gif

Cr0usEEE
06-01-2005, 08:49 PM
there is a 240sx registered for the toledo national tour in SM...but so is my buddy Sean Caron in his 95 DSM and Mark Daddio in his Evo...

we shall see how it compares.

should be a good time though, i will not be competing at this event...maybe devins but you never know.

I hope for my 240sx to one day be a SM contender...stupid school