de-tuning a race engine

Problems, ideas and comments specific to engine swaps.
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ray23
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de-tuning a race engine

Post by ray23 » 27 Aug 2018 07:07

whats up fellas! I'm new to the realm and looking for some info on how to detune a race engine, also this engine is his ready spare engine, so it has been gone thru already. I only have small details for now and I am trying to get the build sheet. info I know is the engine has 13:1 compression, 7-9K rpm power band, cams are custom ground (a lot of duration), its has a dry sump pan and by looks of it the head is ported larger than stock. My plans are to make this engine street-able, reliable and have the power when I need it, HP goal is moderate 200-250. I've looked into buying a complete used unit (1k and under) and rebuilding it myself, but for the price of forged stroked crankshaft is (2K) already not to include con rods and pistons etc etc. for the price he's selling it, I think is a bargain and decent starting point. I've gotten quotes from shops for a drop in stroked 2.3 10K.
Ray
72 Datsun 510 2 door
86 Ford F250 extra cab 6.9 turbo Diesel 2WD

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bertvorgon
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Re: de-tuning a race engine

Post by bertvorgon » 27 Aug 2018 08:43

A lot of things going on here, I'm maybe not the best to explain, but,...

11:1 is still pretty high for pump fuel...a few of us have been there...

with milder cams, that effectively increases the "dynamic" compression, which is not what you want.

http://www.badasscars.com/index.cfm/pag ... /prd68.htm

I lived that too, my "big" cam let me ALMOST be able to run 94 octane fuel with a static cranking pressure of 160, with my "smaller" cam in, my cranking pressure went UP to almost 200 PSI, which meant when I just breathed on the throttle, the engine detonated...THAT you never want.

Horsepower does not come cheap, just a reality. Rebello's price is on the money and you get an awesome package. While your HP goal is "moderate" it is up there from a stock KA ( injected), where with a good exhaust you would be in the 160 range. We have members here with that sort of setup and it is a very nice "street" package, tractable with a nice power band. Our cars are light!

A "well balanced" car is really about the handling too, I would concentrate on making the suspension and tire choice the main priorities first, then the engine/transmission and final gearing. A good handling lower power car will beat a high HP car with evil handling any time of the day.

Some thoughts at any rate.
Last edited by bertvorgon on 28 Aug 2018 04:37, edited 1 time in total.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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ray23
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Location: Temecula, Ca

Re: de-tuning a race engine

Post by ray23 » 27 Aug 2018 09:25

thanks for the reply, I've address part of the suspension, I've recieved Dave's (FUTOFAB) LCA/TCA combo, got the weld on rear camber adjusters from an Australian vendor(referred by DATSPORT). Still undecided about the rear spring/shock set up, but more leaning towards a weight jacker kit vise the coil overs. fronts will be coil overs-just not sure who's-either Troy's 2stage or other company's like T3?(any suggestions?). I have 2 R160's already, I'll have to look inside and see what gear/s are in there. Might either make it LSD or find an R180 3.90 that's already is. Transmission would be a stock 240sx as soon as I find one.
Ray
72 Datsun 510 2 door
86 Ford F250 extra cab 6.9 turbo Diesel 2WD

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icehouse
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Re: de-tuning a race engine

Post by icehouse » 27 Aug 2018 12:24

Just get an SR20. Done and done.
"People don't like it when shit doesn't match their rule of thumb." Sam

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bertvorgon
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Re: de-tuning a race engine

Post by bertvorgon » 28 Aug 2018 04:43

For what it is worth, I fixed my link to the site that talks about cams and how they affect compression:

http://www.badasscars.com/index.cfm/pag ... /prd68.htm

It's interesting as I lived that one for sure, way too big cam shaft for the task at hand. Top end was pretty spectacular though....
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

Three B's Racing
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Re: de-tuning a race engine

Post by Three B's Racing » 28 Aug 2018 05:37

What Ice House said!!! I'm running the SR20DE S14 NA version. Stock its 165hp but I've installed Tomie Poncams, Free flow exhaust and a 10# aluminum fly wheel. Easy to drive and can drive it like stock but when you want it it is there for your entertainment. Reliability awesome as this setup is about 12 years old now and gets driven to the Virginias every year and last year was driven to Canby Oregon and this year Road Atlanta. Not sure I'd want a high compression, carbed 200-250 hp engine for my needs plus having to run high octane fuel and lousey milage. I get 32mpg on highway and run 89 octane all day long no problem. Ka's are awesome engines also and will serve you need for power. Of course there's always the SR20DET for your easily achievable reliable 250hp want.
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ray23
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Re: de-tuning a race engine

Post by ray23 » 28 Aug 2018 06:27

good read, bertv. thanks plenty. I'm really after the goodies thats already in and that's been done on this race engine, so depending on what info the build sheet has I can go from there. Playing around some compression calculators, I'm thinking pistons swap and thicker gasket to lower the CR and address the cams to get that flat torque curve and low end torque back (let me know if I'm off base here bertv.). Icehouse/Three B many thanks as well. Believe me I've been fighting the urge to install a JDM. to make a long story short-I'm a Dinosaur-I don't buy anything on-line, love/hate relationship with computers, and FB for just 3yrs. Being stationed in Japan a couple of times-new car parts are expensive, used parts easy to get if you know the right people and know where to go. I want too be able to go to the local parts store and get what I need if the need arises.
Ray
72 Datsun 510 2 door
86 Ford F250 extra cab 6.9 turbo Diesel 2WD

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icehouse
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Re: de-tuning a race engine

Post by icehouse » 28 Aug 2018 08:47

I've never got a bad engine from an engine importer and installed a ton into 510's (Me, Frank and his son Dillon used to install them all the time for people). I'm sure there is a local shop you can order one from. I've personally never ridden in, or driven a built NA car that was all that impressive, power wise. I'd keep it cheap or go with a turbo. I have the same setup as Three B's in my daily. S14 NA SR with the biggest cam's stock valve springs will allow. Super fun, I do really good in the RWD unlimited class I autoX in. We also have the same engine in our Enduro car. It takes a beating and doesn't even care. I have a turbo SR in the works for it though. Lot's of guys have flex fuel turbo builds. Needless to say after ridding in those cars everything feels slow.

I guess I'm just saying don't break the bank to get this NA motor going when there are lots of options for power and reliability at a cheaper price.

Like our buddy Hienz says "A guy will post a picture of a 510 lug nut he got for free and spend a zillion dollars building the car around a free lug nut instead of waiting for a nice car to come up for sale at a fraction of what he will have into that lug nut." Hienz says it better!
"People don't like it when shit doesn't match their rule of thumb." Sam

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ray23
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Re: de-tuning a race engine

Post by ray23 » 29 Aug 2018 18:04

Its been a pain in the rear finding a complete KA24DE with trans here where I'm at. I might just throw that rebuilt L18 back in and call it a day.
Ray
72 Datsun 510 2 door
86 Ford F250 extra cab 6.9 turbo Diesel 2WD

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funwithmonkeys
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Re: de-tuning a race engine

Post by funwithmonkeys » 29 Aug 2018 20:10

I bought a detuned race engine 5 years ago and have never been happier. It was a LZ 2.3L with 14:1 compression when Andy showed it to me. He got new pistons to bring it down to 10.5:1 and put smaller chokes in the dual 44's. It was a LOT of money but 8000 rpm in a L series is awesome. Dry sump will take some work to get in your car but you would be able to get the the engine lower than one with a oil pan on it. I have a 580 lift cam that everyone seems to think is too big for street use but I love it. It idles great at 1200 rpm and has a great powerband from 4000 to 8000.
If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?

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ray23
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Re: de-tuning a race engine

Post by ray23 » 30 Aug 2018 12:07

his selling this KA for 4k, how much was yours?
Ray
72 Datsun 510 2 door
86 Ford F250 extra cab 6.9 turbo Diesel 2WD

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funwithmonkeys
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Re: de-tuning a race engine

Post by funwithmonkeys » 30 Aug 2018 18:27

Much more than that....you are probably looking at another 2 to 3k to get the lower compression pistons and for the work.
If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?

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bertvorgon
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Re: de-tuning a race engine

Post by bertvorgon » 30 Aug 2018 19:07

As I said, HP does not come cheap, and hopefully with the right builder and $, you have RELIABILITY!

I won't say what my motor cost but I am into my 17th year with this thing and it has been used hard on occasion to say the least. Built right, good fuel and oil..and NEVER let it detonate.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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funwithmonkeys
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Re: de-tuning a race engine

Post by funwithmonkeys » 30 Aug 2018 21:02

What Bert said....I paid a lot but it was worth every penny to be able to flog on it like I do and never have it miss a beat in 5 years.
If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?

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ray23
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Re: de-tuning a race engine

Post by ray23 » 30 Aug 2018 23:21

bert what engine you running? funwithmonkeys how about you what engine you running? I'm a mechanic and not an engine builder by trade. I can easily put things together with no issue, but thats about it. I would need some sort of direction or calculator to tell me what I need to throw in there. I have a little bit of measuring devices-feeler gauges, venier caliper(in&out) and a depth gauge, but the biggest factor is experience or lack of it. My assumption was close to your estimate bout another 2-3K to get it where I need it. I know its really temping to go S15 for less (3400), but I'm sticking with the USDM units less head ache in the long run IMHO. if I cant find a parts i need to get the KA running then I would just work with the L18 I already have and add some webber 40 dcoe. and headers.(not gonna reach the 200HP mark).
Ray
72 Datsun 510 2 door
86 Ford F250 extra cab 6.9 turbo Diesel 2WD

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