Engine build sheet

[tdenardoKAT26]

Hello everyone, I have a 93 fastback with the ka24de. After tons of thought I decided to build the ka. Here's the question:
If airflow =(goal hp*a/f*bsfc)/60
Then map=airflow*gas content*(460+ intake temp) divided by VE*RPM/2*CI displacement
Where gas content=639.6 and intake air temp =130

This should be the result if I stroke to a 2.6 and rev to 6800
(425*11.5*.55)/60=44.8
(44.8*639.6*590)/(.95*3400*158)=33.12
Subtract perfect day atmospheric pressure (14.7} and you get 18.4psi required for 425.
I see ka24de pushing similar with 16psi and still at 2.4. Am i missing something? Also, how do I take into consideration hp gains with items such as head porting, cam upgrade, intake manifold upgrade and throttle body upgrade?
Any information is greatly appreciated! Thank you everyone!

[compactfean]

There are too many variables to let a formula guess your horsepower to a tee. Dynos alone differ. Tuning the Ignition timing and using an alternate fuel alone could vary 100 HP on some motors.

[tdenardoKAT26]

As far as fuels go what is the max cylinder pressure to be able to safety use pump fuel? That is a big must for this build, and is there any way to calculate what your cylinder pressure will be considering compression, displacement and boost?

[compactfean]

Well if your not bored out than just go by the stock numbers. As far as boost im sure there is a way to figure it out with some blueprinting software. Im boosting 14 psi with 9.5 to 1 CR (same as ka) on my b14 sentra with a jwt ecu and 50lb injectors on a daily driver on pump gas. I think your thinking too far into it for a pump gas build. What are your goals /purposes for this car?

[tdenardoKAT26]

I am trying to push 400-425 horsepower to the crank on a ka24de bored and stroked to a 2.6. Its not going to be a daily driver, just something to use on weekends and take to the track once in awhile. Where can I get blueprinting software? Im just trying to make sure everything works before i spend the money on everything and something goes wrong.

[compactfean]

As far as blue print software who knows....I got a blueprint printout of my motor but I have no idea what they used to give me those exact specs. I see where your going with the whole running more displacement for more power with pump gas but a ka already has overheating issues and with a stroker ka will heat up even more. The ka already has a 90 something mM stroke which is alot. A bad a** oil and coolant cooling system will be a must. Other than that really good main and rod bearings that have optimal heat and friction resistance. Also, very important, the crank must be fully counterweighted. Other than that the normal build stuff, MLS headgasket, head studs etc. I don't see why you couldn't hit 400whp at 16-18 lbs with your setup. Putting that much work into a motor though I'd be aiming for higher boost and higher numbers. There is a Guy on here running STOCK motor with Turbo tuned on 101 octane hitting 500whp.

[tdenardoKAT26]

The only reason I am doing a stroker motor is because the kit has a good crank. I can't find an after market crank for the stock ka specs anywhere. But i do know what you mean about the over heating issue. I bought the car with 182k miles on it and the only way I could keep it from over heating was pull the thermostat. I would love to keep it 2.4 because the 2.6 are kind of scary as far as the moving mass. Seems like a good chance of failure.. Not to mention the savings on the build by avoiding the stroker kit what's your opinion on the acl dura glide bearings. I've used acl on a honda build I've done and never heard of their dura glide. They are the only ones i could find for the ka that seemed worth it.. Btw, do you know what boost that guy with 500whp is running? That'll give me an idea what I can run at with 101.

[compactfean]

Im not sure on the " dura glide" but you could call them and tell them your build and see if those bearings are right for you. I run acl bearings in my SR and my girls b16 Honda with no problems. That Guy was boosting 24 psi Max. As far as your crank, you could get it machined back to spec and fully counterweighted at a machine shop or Brian crower makes a nice fully counterweighted. Stock spec crank. Im not sure how much machining the stock crank for all that but my local machine shop quoted me 450 to stroke out my crank and I'd just have to buy stroker pistons or rods. I think the BC crank is like 1400, which for a forged fully counterweighted crank is not bad.

[tdenardoKAT26]

Where did you see the stock spec bc crank? I'm using all bc internals but the only crank i could find was the bc stroker. He's not having any detonation issues with 24psi on 101? That sounds nice. 101 shouldn't be to hard to find, and for the power sounds worth it.

[sly240]

Ok while trying to keep this short first thing is your math. For your VE (volumetric efficiency) why did you choose .95? On an N/A engine this would be very good but you are now boosting your engine so your VE will go up how much depends on to many factors to list. But I have seen formulas with VE at 1.05 or 1.10. (By the way all the all the things you listed like head porting, throttle body, cams all have a big impact on VE.) While I mentioned cams a good set of cams can make or break an engine and there is way more to cams than lift & duration (overlap, opening ramp, closing ramp, and max lift duration to name a few) 2nd There are too many variables to truly predict an engines power. But the formula does get you in the pall park. I said I try and keep it short so good luck and if your already going through all the trouble on this math than don’t forget all the math for your turbo, exhaust, fuel system, intercooler efficiency, ETC!!

[tdenardoKAT26]

I got the original formulas from turbobygarrett.com. I have built n/a setups before, but never turbo. I just know there are a lot more variables to consider. I know there is no way to get the hp prediction to a tee, but I want to make sure I get the correct injectors, fuel pump, etc...

[TonkaTruckin]

All I can say is.. buy some books. You seem willing to learn the art and there are countless books out there that can point you in the right direction. Plus, there is nothing more rewarding than building the motor you want, the right way, and having it last for years of enjoyment! Of course that is allowing for periodic tear downs to inspect bearing surfaces and measure clearances and what-not.. but you get the point. If you need some book ideas to understand turbo dynamics and how they interact with a motor I have a few that have helped refresh my memory a few times after school..

[tdenardoKAT26]

Yea for sure, I would love to gery done suggestions on those books

[TonkaTruckin]

Ok, so some good books I have read are "Turbocharging Performance Handbook" by Jeff Hartman, there are lots of pretty pictures and some good math to back up the principals so you can apply everything to your build. "Maximum Boost" by Corky Bell, more math and a more scientific approach to turbos, less pictures, more good stuff. "The Racing Engine Builder's Handbook" by Monroe (hp books) its a great start for blueprinting your own motor and getting an idea of what you need for a "happy" and efficient motor. And finally "designing and tuning High-performance Fuel Injection Systems" by Greg Banish (s-a design) fairly easy to understand introduction to fuel systems in general. Once you build the motor you want it to run well right?? you should be able find these books at any barns and noble or borders. good luck! and remember, you can never have enough books!

[compactfean]

Where did you see the stock spec bc crank? I'm using all bc internals but the only crank i could find was the bc stroker. He's not having any detonation issues with 24psi on 101? That sounds nice. 101 shouldn't be to hard to find, and for the power sounds worth it.

damne its been years since ive looked up parts for the ka. im almost %100 it did exist but i cant find it. but in doing so im growing fond of that bc stroker kit. it seems that the ka motors flaws for the bottom end have been covered in that stroker kit.
#1 lack of lubrication on crank and rod bearings cylinder #4- solution was to make the crank have individual oil supply for each journal through the crank.
#2 the crank not beeing counter weghted. problem solved by counterweights.
#3 with a stroker kit there will be more stress on the bottom end.... to relieve some of that stress notice that the crank has a better "knife edge" than stock.
im not sure if you have checked with a machine shop yet but to fix what ever is wrong with your crank and counterweight it im guessing you would probably spend 700-1000$. plus pistons and rods another 1000. the stroker kit is 3,000. so the big question is, is it worth 1000 difference to get rid of the lubrication issue on cylinder number 3 and 4, get rid of the counterweight issue, and a decent knife edge and .2 liters and a very strong crank. OR machine the stock crank, save a ton of money, could possibly have oil issues on 3 and 4 (if your doing a rebuild with new oil pump is unlikely) still get rid of the counterweight issue BUT have a crank not as strong as the BC crank? in my personal opinion the benefits of the stroker kit out weigh the 1000 difference. the only down fall is this motor stroked is deffinately not gonna be a 9,000 rpm motor but the power you make down low could make up for it.

[tdenardoKAT26]

TonkaTruckin, thanks for the book ideas. Definitely sounds helpful! I've built N/A setups before but counting all the variables into a boost setup is where I have some learning to do. I appreciate the advice! Compactfean, very good points! I did, however, locate a BC fully counter weighted and forged stock stroke spec crank. But the stroker kit is very tempting