Im really thinking of pulling the U20 for an SR20

toolsnob · Post by **toolsnob** » Wed Mar 16, 2005 10:20 pm

Ok, I will ring in...I can tell no one else here worked 12 hours today!

My reasoning... if cost is the big issue, go KA. A guy can sell a good running U20/5speed for the cost of a ka drivetrain and still have money for some new panasports.

But if performance is key then go SR, lighter weight and newer tech make it very appealing, I would look towards the turbo myself.

And a KA bottom is not bullet proof... I have heard that the later KA's actually have weaker bottom ends vs say a 199-93 model. Many a KA blow the bottom end if you boost more than 8psi. Plus by the time you turbo'd a KA and bought a stand alone ignition system you would be into it as much as a KA anyway.

Now, I have fabbed in both the KA and SR's into roadster. The Ka does take less fab but the fun part about working on the cars is working on them! So I don't see the little triming you do to the crossmember as a deciding factor, and all you roadster folks worried about not cutting up the car so that you can go back to a stock drivetrain will never convert back to stock after you have a modern drivetrain.

So, after I swap a couple more customers cars I will be going Sr20DET and go U20 hunting in SLO!

Alexi

Post by **spl310** » Wed Mar 16, 2005 10:49 pm

[quote]So, after I swap a couple more customers cars I will be going Sr20DET and go U20 hunting in SLO![/quote]

Man, with you and Alvin hunting, Will better look out!!

BTW, Alvin, did you and Will ever have the showdown? If so, what gives??

Ldino21 · Post by **Ldino21** » Thu Mar 17, 2005 12:17 am

I have heard it all before, and all that matters is that they all make it to Solvang in April so we can compare them side by side!!

Lou Smaldino
66-1600 (KA24DE)
67-2000
65-1500

roadsterdude · Post by **roadsterdude** » Thu Mar 17, 2005 12:51 am

spl310 wrote:
So, after I swap a couple more customers cars I will be going Sr20DET and go U20 hunting in SLO!
Man, with you and Alvin hunting, Will better look out!!

BTW, Alvin, did you and Will ever have the showdown? If so, what gives??

OH man..what did I just open up here..
Im sorry if this thread has been asked before.

And Im sorry that I didnt mention about the KA route.
The only reason that I mentioned the Sr20 exclusively is because
I have driven Alvin's sr20 roadster, and I havent even been in a
roadster with a KA.

From the sound of it , either swap is a great swap..
My question was also about the performance gain when one
goes from a U20 solexed powered to either a SR or a KA .
Is the perfomance really worth it?

Has the KA vs U20 shootout been done ?
Or the SR20 vs U20 ?
Maybe even the KA vs SR??

Thats what I wanted to also see. how much of a performance gain
is it..
Sure the KA and or SR20 are really reliable..etc..I have heard all of that...so in that sense..the swap is definitely a plus..

But what about the perfomance...

So Alvin...what happened with Will's Monster U20 and your SR20 ??
Has that happened yet?

So if anyone has any experience with those aspects please let me
know..

And again Thank you all for you inputs...they are greatly appreciated.

This is one of the reasons I asked the question here.
I know I will get the answers I am looking for.

Raul

TR · Post by TR » Thu Mar 17, 2005 1:00 am

As we were going through SF, Alexi and I were playing car tag. I got a clear spot in second gear...I think Alexi's quote was, "I have never seen a roadster launch like that, a little squat of the back end and bam" Maybe it wasn't 'bam' but some other John Madden type of 'wow!'. He was driving his U20 equipped car...

And back to the age old debate...

I just can't see wanting any more torque. Yes, we all know torque is what turns the wheels, but if those wheels are not sticking to the road, it is all wasted. And with a low redline and all the shifts that come with it to use that torque, I'll take the higher revving engine in a traction limited car any day...TR

roadsterdude · Post by **roadsterdude** » Thu Mar 17, 2005 1:08 am

TR wrote:As we were going through SF, Alexi and I were playing car tag. I got a clear spot in second gear...I think Alexi's quote was, "I have never seen a roadster launch like that, a little squat of the back end and bam" Maybe it wasn't 'bam' but some other John Madden type of 'wow!'. He was driving his U20 equipped car...

Now..TR.....I believe yours is an SR20DET...now theres a big difference there..Im asking about the normally aspirated beasts..

I could only imagine what if feels like riding in that roadster of yours. Whooo HOOOOOOOOO.

spriso · Post by **spriso** » Thu Mar 17, 2005 1:13 am

Wow, never take a day off reading the 311 forums, all kinds of good stuff happen when you are gone!

I have never driven a KA powered roadster, but I have driven plenty of 510s with this swap. The KA is a good engine, cheap, easy to find parts for, etc.

But it does not rev like a SR, and that is more in keeping to what I feel the character of our cars is all about. The SR swap is light weight, free revving, and in my mind is the perfect engine for this chassis. Start putting anything heavier and the car looses its wonderful handling and nimbleness.

All we do is SR swaps; I have no interest in putting a KA, FJ, CA, or VG into a roadster chassis... SRÃ¢â‚¬â„¢s is all we do, and our cars work, very well. The KA vs. SR swap argument will never be settled-- but know this-- either way, there is no way that a U20 is going to catch up with technology...

Michael Spreadbury
Spriso Motorsports
SR swaps a plenty!

TR · Post by TR » Thu Mar 17, 2005 1:18 am

Yes it is the turbo, but given:

KA 150
SR20DE 140
S13 SR20DET 200
S15 SR20DET 250 (childhood giggle)

Compared to (my guesses - here comes the screaming):

R16 90
U20 120

"True" HP, upgrading is an easy choice. What, better mileage and more HP? Ain't technology great?! TR

nomadtrash · Post by **nomadtrash** » Thu Mar 17, 2005 1:35 am

My KA revs at least as well as a U20 with a B cam and Solexes. It hits the rev limiter at 7000 rpm's just like my U20 did. I had a very hot U20 with a 296 degree cam, high compression, race gas, etc... and the KA is much stronger. My KA is in a mild state of tune compared to my U20. I found that the U20 didn't like to live very long above 7000 rpms just like the KA.

I do have problems hooking up with all that torque. I think it is in part to the not so limited slip rear end. I need to repack the posi. It still out accelerated the Z06's at the autocross last Sunday.

I do have a rollbar mounted cam. I am having technical difficulties with it. The ride is too rough and the g-forces are too much for my camera. The tape heads are skipping and fluttering while recording. The picture is pretty good at slower speeds but around the high-g corners and full acceleration it cuts out.

My g-tech showed 1.25g cornering on Sunday. I didn't get any good readings on 1/8 or 1/4 mile times. I'll take it to the local drags and see how the new motor compares to the 10.05 I ran with the old U20, slipping clutch, and 2089 pound car.

TR · Post by TR » Thu Mar 17, 2005 1:40 am

Although not a direct comparison, it will be interesting to compare the drag times.

I love how much interest this debate always brings. Nothing gets someone typing like hearing/reading that someone else thinks their engine is better!

I hope the discussion is fun for all, TR

spriso · Post by **spriso** » Thu Mar 17, 2005 9:06 am

Just a quick correction on your horsepower numbers Travis:

KA24E: 140hp (240SX version-- less for pickups)
KA24DE: 155hp (both versions of the S13 and S14 240SX)

SR20DE: 140hp (S13 Silvia)
SR20DE: 160hp (S14 Silvia-- has VVT)
SR20DE: 165hp (S15 Silvia-- has VVT)

Alvin's car is running an S14 SR20DE, so it should be in the 160hp range (at the crank).

My car in it's original configuration used the S13 SR20DE and put 130hp to the rear wheels-- not bad for an engine that is rated at 140hp at the crank!

When it goes back together I have a S15 SR20DE, so it will be interesting to dyno the changes to see what we really picked up in horsepower and torque.

Michael

TR · Post by TR » Thu Mar 17, 2005 11:59 am

Thanks for the corrections and additions! Were my DET numbers correct? I noticed you didn't comment on the stock estimates? I love to beat that drum...

92% efficiency for your drivetrain is pretty good. I've always heard to estimate 85% from crank to wheel. Maybe that is old school V8 tranny efficiencies, though...

The HP estimate from my g-force meter on the roadster comes up with 110. Granted I haven't learned how to launch without wheelspin and the zero to sixty times are weak because of it, I'm still surprised at the estimate. Anyone else have any luck with the HP function on a g-force meter?

Maybe when I get the 510 built up, I'll take both cars down to a dyno...TR

DELETED · Post by **DELETED** » Thu Mar 17, 2005 12:17 pm

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spriso · Post by **spriso** » Thu Mar 17, 2005 12:17 pm

Your DET numbers were very close.

I forgot another version of the SR20DE:

S15 SR20DE (Autech version): 200ps (197.2 hp)

As for versions of the SR20DET:

S13 SR20DET (Red top and black top): 205 ps (202.19 hp)
S14 SR20DET (Black top w/ VVT): 225ps (221.9 hp)
S15 SR20DET (Black top w/ VVT): 250ps (246.5 hp)

ps is a metric hp rating and is something like .98 of a hp, so your numbers are very close to correct.

Michael

DELETED · Post by **DELETED** » Thu Mar 17, 2005 12:32 pm

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Datsun Roadster Forum-311s.org

Im really thinking of pulling the U20 for an SR20

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