budget motor build q's

[hondamanlxi]

Well the n2o finally got the best of my motor and i got a mechanically sound motor from the j/y. This motor/head will be completely (re)built b/f i put it in...

1) I wanna get to 10/1 comp without spending 700 on diamond pistons/rods.How much can the block be decked? How much can the head be shaved?

2) I know the stock head cfm is 135, but how many cc's? Intake especially

3) Is it true that ls pistons are the same size? Are they higher comp?

4) Has anyone found stock valves from any car that are the same installed height but bigger?

please understand i cant afford diamond pistons,titanium valves/retainers,or any high dollar shit! This in no way means im doing this half-assed!

thanks guys

[Chicane]

I hear the unobtanium pistons are better than the diamond ones. ;P

[AccordEpicenter]

nothing youre gonna do is gonna be cheap here. Valves and the bigger pistons will cost you out the ass. Youre gonna need some good rod bolts, you can use stock rods but id have them shotpeened. LS pistons are the same bore i belive, but... the pin height is different (you cant use them). With a good cam and head port youll outflow the stock cam with oversize valves and a mild port etc. You can safely take these engines to 7250 rpm on a stock valvetrain if its in good shape, but i wouldnt do it very often on stock pistons/rod bolts, aftermarket pieces are lighter and resist the flex that such a high rpm load will have. With the stock replacement forged pistons from diamond you should be able to keep your stock rods if you have the small end enlarged from 19mm to 21mm at a machine shop. Also a better intake manifold will help boatloads? how much hp are you shooting for?

[3gn86lxi]

HP=$$$$$$$
Spend it wisely. :alc:
It will take money to make true horsepower.

[hondamanlxi]

you know what, nevermind! Ill just build it and show you that SOME money in the right places can really help!I know performance isnt cheap, budget is a relative term! Thanks for treating me like im dumb Im only shooting for 200hp b/f spray
mods to date

not listed is the crower cam i ordered from vinny

[Chicane]

200hp out of a 2 liter that normally makes 98-160ish? Good luck! Hope you can do it, it'd be cool.

[A20A1]

There was a 300 + A20... not sure if it was N/A or nitrous injected.
It had quad bike carbs.

I'd just shoot to keep improving what you've got, whatever the hp is you'll at least be better then it was before... sooner or later you'll hit 200.

I would jump at the chance to pop in a larger exhaust valve seeing as we only have one to play with... but that's money I don't have.

Did you ever end up getting a larger TB?

[A20A1]

1) I wanna get to 10/1 comp without spending 700 on diamond pistons/rods.How much can the block be decked? How much can the head be shaved?
...

Ah, don't shave, do what Openloop did and weld the inside of the chamber to increase compression... this way you still have good deck height for safety of your valve train. and you don't have the added expense of fitting in custom made high comp pistons.





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[hondamanlxi]

thanks alot a20a1! your attitude is why you deserve AOTM!

a20a1: ill keep you updated on my quest for STOCK REPLACEMENT valves that are 1mm bigger on the intake and 2mm on the exhaust! Im not sure what car theyll come from but ill find em

[AccordEpicenter]

well 200hp n/a before spray is quite a project... I seriously doubt it could be done without some seriously big cams and huge port work

[hondamanlxi]

big ports YES! big cam eventually! I dont know how to make the ecu happy yet

[Vanilla Sky]

persoanlly, i don't like that welded head... it may raise compression, but it screws up what honda put millions of dollars into for design... the shape of the head is the shape it is for a reason... having an oddly shaped head goes against what i know about head design... i think you're better off with the high comp pistons or a shaved head... anyways, i thought most people that built nitrous motors dropped thier compression...

[AccordEpicenter]

youre gonna need either a chipped ecu from a different car (somthing that you can control timing with) or standalone or somthing... fine tuning N/A has to be more exact then for turbo for big power gains... Turbos you can ballpark it if youre on the safe side of things.

[hondamanlxi]

vanilla sky, thats the whole thing, Im trying to get off the spray! I want it to be kinda like backup

[A20A1]

persoanlly, i don't like that welded head... it may raise compression, but it screws up what honda put millions of dollars into for design... the shape of the head is the shape it is for a reason... having an oddly shaped head goes against what i know about head design... i think you're better off with the high comp pistons or a shaved head... anyways, i thought most people that built nitrous motors dropped thier compression...

Is it the path of the flame kernal or how the air flows thru the intake and to the exhaust that causes so much trouble with welding it?

In my view a smaller space will flow the gasses at a higher velocity, but that effect may only be relavent durring a short period in the engine cycle.

However
What I don't like is the little " V " notch near the spark plug... it may effect the efficiency of the intake stroke some durring the overlap period.

Also the filled in area has a straight edge instead of a chamfer... that may effect things on the exhaust stroke.

But I'm only guessing here.

Anyways what is shown may be a bit extreme.. you may only need to fill in less then what is show to achieve the comp ratio you want or go for the A18 head.

[Chicane]

I really think that's going to be damn impossible unless you stroke it, run insane RPMs or something. Ever heard of MEP? Google for MEP.... it's basically the efficiency of an engine..... for example, an s2000 has a mep that's pretty high... the corvette z06 has a fairly bad mep.

HOLD ON! Even though the s2000 has a higher mep, it has a quite narrow powerband making it kinda suck for street use, and the Z06 with it's old school technology and shitty mep manage to beat the s2000 in every single category, INCLUDING miles per gallon...

Moral of the story? It'd be really really hard to get 200hp out of 2 liters if it's NA. Turbo, sure, nitrous sure, but very very very very expensive to do so completely na. Also, just because you have a higher mep doesn't mean it's going to be a good idea for street car.

- Chicane

[Vanilla Sky]

mike, i'll take the first answer for $100... that and the fact that you want everything in there opened up, not walled off like that welded head...

chichane... the s2000 and vetter use two motors, each of which are pretty much polar opposites... the vette has a v-8 that has gobs and gobs of torque... it has a decently smoothe and wide power band because of the fact that it's a medium displacement v8 motor... the motor in the s2000 on the other hand is a fairly small 2 or 2.2(year dependant) litre 4cyl motor which is tuned to make power much farther higher in revs... because of the natures of these two very different motors, they are going to perform differently... niether is really better than the other... they are just different... though i think if you really got into the throttles of these cars on a racetrack, such as a road course, things like milage will come out the same... on the road, one may get better milage because of other attributes to the car, such as gear ratios, number of gears, shiftpoints... we can go on and on about this......

200HP on a naturally aspirated 2 litre engine may require a lot of tuning and a good bit of money, but it's attainable without robbing the bank weekly... things like crossreferencing parts, such as hondaman is looking into is a good route... i do have to say though that if i were hondaman, i would spend the money on pistons, rods, and a balanced bottom end... may not be a power maker in itself, but it's going to make the motor more reliable due to better made parts, and make the rotating mass lighter, so as to have the ability to rev higher (well, at least until valvefloat becomes and issue)...

one question i must ask is that where do you want to see this 200 HP? at the crank or at the wheels? big difference

[AccordEpicenter]

while im not knocking the vette (i like some vettes) if they made their v8 to honda specs itd be making 570hp stock n/a oem factory... that would be impressive. I dont like that head because it looks like itd develop hotspots thatll lead to detonation with all those added edges and shapes, and thats a risk i wouldnt like very much if i was forced induction or spraying... or even top shelf N/A. For the money youre looking to spend on this project youd prolly be better off moneywise on a small turbo setup.

[Vanilla Sky]

For the money youre looking to spend on this project youd prolly be better off moneywise on a small turbo setup.

yeah, that's what they keep telling me... i wanna see 200 WHP out of our cars without boost and the A20 motor... i think it can be done, too...

[Mike's89AccordLX]

Definately get your bottom end balanced. Build it good from the bottom up and you will reach your goal. I have the same goal of 200hp with my accord. I'm not in any hurry to do it though. I might end up getting a b20a motor and making it carbed

-Mike

[AccordEpicenter]

get some dcoe's

[AccordEpicenter]

edit... im a retard

[Chicane]

I'm posting this from another forum....

I talked with Rob (Chicane) before and he wanted me to share with you a point I made to him. The point relates to "MEP" ("Mean Effective Pressure") MEP is defined as the pressure that would have exist inside the combustion chambers during the power stroke to produce an equal amount of power. This assumes no pumping or compression losses, and no friction. It is purely academic but it can be a useful tool.

If you think about it, MEP is directly proportional to torque. Torque, in turn (or rather, peak torque) is almost directly proportional to displacement. Don't believe me? Grab a car magazine, go through and find every naturally aspirated gas engine you can find. Calculate torque divided by displacement. Almost all engines will be in the range of 90-100 Nm per liter. (You can't count forced induction engines- that changes everything. ) The torque per unit displacement can tell you something about how "efficient" the engine is (but this is only loosely related to thermal efficiency, which is work out/energy in). But, since engines in most cars are designed by competant engineers there is not wide variation in MEP.

Now, with a naturally aspirated engine, you can only get a MEP so high. You can port and polish, put on new manifolds, raise the compression ratio, tune the fuel system, but there is definitely an upper limit to how much pressure (or effective pressure) you can get. What is this limit? Well, no one really knows, but you CAN look at some of the best engines in the world (namely, Formula One) and compare what their teams of 100's of world-class engineers are getting to what you want, and see if it's reasonable. The MEP's in high performance racing engines are typically around 20% greater than in passenger car engines.

Now, as I've said, MEP is proportional to torque. What about power? Well, power depends on WHERE on the tachometer the torque comes in. Power is proportional to torque x RPM, so torque at a higher RPM will get you more power. Putting in high performance cams, for example, does not change how MUCH torque your engine makes, but it changes WHERE on the tach the torque peak comes. It shifts the torque peak up, meaning you make more peak power. But you do this at the expense of low-end torque and power and a smooth idle.

So, if we want to know what the maximum power potential of an engine is, it's proportional to how much air you can flow into it. For a naturally aspirated engine that's proportional to redline x displacement. So, to see how close an engine is to its maximum power potential, you could take POWER(hp) / (REDLINE(kRPM) x DISPLACEMENT(L)) and call that the "power efficiency." This value is related to MEP, but they are not the same because of the RPM effect I mentioned in the last paragraph.

A modern F1 engine makes around 850 horsepower, has a displacement of 3 liters and turns 19,000 RPM. So, the "power efficiency" of this engine is 14.91. Consider this an upper limit for all of your projects (again, this only applies to naturally aspirated engines, and nitrous doesn't really count). A few other "power efficiency" values for high performance engines:

Moto GP - 14.55
McLaren F1 - 13.70
Honda S2000 - 13.33
Suzuki GSX-R600 - 13.22
BMW M3 - 13.01
Porsche 911 - 12.70

For the purposes of modifying your Subaru engines, you could probably take 14 to be a good upper limit.

Now, there are reasons why you WOULDN'T want the highest power efficiency. Rough idle, poor fuel economy, poor emissions, lots of noise, and deficient low-end torque are all consequences of tuning an engine for maximum power efficiency. Take the Chevrolet LS6 engine (from the Z06 Corvette). It has a power efficiency of *only* 10.93. Why? Because GM engineers are idiots? Hardly. The Z06 makes 405 horsepower, runs the quarter in 12.4 @ 116 mph, but still gets almost 20/30 mpg city/hwy. Compare that to the Honda S2000, which has a significantly higher power efficiency. Yet the S2000 makes less power AND has poorer fuel economy. So the “best” engine doesn’t always have the highest power efficiency.

The point is this: you need to figure out exactly what you want from your engine, and then the best way to get it. If you want 400 hp out of your SVX engine (3.3 liters, 6500 RPM redline) you’re going to have to increase the displacement, raise the redline, or add a supercharger or turbo (or nitrous). To do otherwise would require a power efficiency of 18.65, which is impossible. When modifying your engine ask yourself these questions:

-What fuel do I want to use? (regular, premium, race gas, alcohol...)
-Is a smooth idle important?
-Is fuel economy important?
-Do I care about flexibility (broad power band)?
-Do I care about peak power?
-How much money do I want to spend?
-How often to I want to rebuild it?

Invariably you’re not going to be able to get everything you want, so you need to set priorities. It’s a very complicated process, one for the most part I can’t help you with.

Rob wanted me to stress the fact that the power efficiency of the stock engine, 10.72, can be improved. He is correct. However, there are consequences to everything you do to your engine. Like I said, figure out what you want, and then the best way to get it.

[Chicane]

Basically, the honda version of the v8 would not make that much power... UNLESS it had the same RPM... the chevy's engine is not a dinosaur, nor is it outdated. In terms of MEP, it loses, but in terms of power, torque, powerband, and fuel mileage it wins. All with a lower mep.

[Chicane]

Also, you can't just use simple math and say "Honda made x amount of hp with 2 liters, so if I made a 6 liter honda engine it would make 3x amount!" It doesn't work like that. Bigger engines have heavier internal components, more moving mass, and they will naturally rev LOWER than small-displacement engines. This means that with a smaller engine, you can use revs to increase your mep.. with a larger engine it will have lower revs.