200whp. NA. What does it take?

[Installshield 2]

Actually, no, but that's a great idea, although a bit tougher to do. However, when i optimized for hp, the volumetric efficiency got as high as 96%, which I thought was phenomenal. Torque peak was around 160 ft*lb with 150 at 1500 RPM lower and higher.



No, I don't. I probably should get it, although I'm really busy trying to close on a house, get married, and start my first job. I'll get around to it.

Is that flow based on the head, or bolt ons? I would understand if the head had better intake flow. There's a ratio that has to be optimized with that, but I forgot what it's called.



I understand about the rod ratio. It helps that most honda engines (minus the CR-V, some accords, etc with the 2.4) are relatively square. They also have a tall block. In a perfect world I'd get a miata crank and some longer rods to keep or increase the stock compression ratio. .2L of displacement doesn't seem like much when you consider the RPM benefits. Is the FS block any taller? I mean, after destroking, could the FS have a better rod ratio than the BP?

Most cars seem to run extremely rich, starting at the torque peak. That sucks because 70-75 mph is right in the torque peak and it sucks down gas on the highway at that speed. My other car, stock, runs 11:1 A/F past 3000 RPM. It's torque peak though is at 1800-3200 RPM.

Thanks for the replies. I know the FS isn't a great engine for modding, but if you consider that if you spent the same money on bolt-ons or top-end (valvetrain) parts as you did with a different engine, you'd get less output, but the car is already a blast to drive, and any improvement would just make it more fun. I'd be satisfied with 130 whp, knowing how many tickets I'm going to get when the car is stock....

Here's my plan for 130+ whp:

CAI (no hp increase, but sounds a shitload better, and cleans up the engine bay)
header
2.25" cat-back exhaust (custom, because chrome is for douches)
cams (lift has yet to be decided, based on vacuum and head flow)
intake (221 dur, -4BTDC, 45ABDC)
exhaust (236 dur, 50 BBDC, 6ATDC)

I don't like the overlap issue, but run that through DD and let me know if you can come up with something better.

Oh, and an ECU rePROM

If you destroke the FS engine, you essentially make it the FP...which is the same for the most part, just less stroke and 1.8L...I am not positive on what happens to the rod ratio's on "destroking" an engine when you don't do anything to the crank...I haven't read up on that in a while, but to my understanding nothing would happen to the rod ratio's unless the crank geometry is altered as well...Some one clear that up though, that may not be right...

But that engine makes about the same overall output in HP as the FS, less torque, and is much more willing to rev...it generally is said to be a slightly better starting point for NA...

 

[iluvmacs]

Install:

the only thing that would change the rod ratio compared to the FP, would be if and only if the deck height was different on the FS engine. To compensate, you'd have to use longer rods or you'd lose your compression ratio. The piston wouldn't travel far enough in the cylinder. If they're the same block, nothing changes though.

edit: the FP probably has longer rods to begin with, but what I meant was even longer than stock FP rods, if the block was taller.


MSP:

most FI guys never look into valvetrain work. the reason is this; the engine is designed to have a flat torque curve at some point in the RPM range. The turbo also has a maximum efficiency curve, which can be set before (more torque, usually stock setup), at (maximum torque), or beyond (hp, and big turbos) the engine torque range.

When you change cams, do not increase overlap, as you'll lose all your boost to the exhaust.

Cams and head work make the turbo have less work to do, and thus increases your turbine efficiency, and lowers your intake temperature. usually it's much cheaper to intercool or increase boost to get the power you want.

If you want a super KA engine, design the turbo for a certain RPM range as most FI guys do. Then, rebuild the engine, with cams, headwork, and manifolds to compliment the turbo.

Slapping a turbo on isn't really tricky, but true efficient turbocharging requires modifications to the intake, head, and cams.

 

[MSPinVA]

thanks iluvmacs. I was talking about WAY down the road, as the FSDE motor cant take too much past moderate boost on the stock bottom end anyway. I figured if I was going to take the motor apart and do the rods/pistons, I might as well do the top end too. I figure doing it right the first time is the best way to go

 

[iluvmacs]

If you've got the funds. Valvetrain work is the most expensive compared to the other stuff you're probably going to do.

 

[twilightprotege]

macs - yeah the intake side flows more - based on the size of the valves and the flow test i had done after my head was ported

and your cam specs sound good on paper, but the intake needs to open earlier. i'd strongly suggest adjustable cam gears

 

[akhilleus]

Those cam specs seem kinda high on the duration end. I would really suggest minimizing the duration increase and increase lift more. High duration ruins your bottom end. no more than 220@.050"

 

[iluvmacs]

twilight: Those specs I got from optimizing the setup on Desktop dyno. I used your head flow specs, since they're the only numbers that the cylinder head can be calculated with. I plan on getting cam gears, and do much more research with cams.

akhilleus: The point of the duration was to decrease bottom end power. Reasons... top end torque means more hp...the FS-DE already has plenty of torque, less won't make much of a deal to me...I need gas mileage when not driving the snot out of the car. I'll check on the lift, but I want to do some research into vacuum effects and the need to increase idle speed.

 

[akhilleus]

Alright but look at twilight his powerband went way up with similar duration.

 

[Installshield 2]

Install:

the only thing that would change the rod ratio compared to the FP, would be if and only if the deck height was different on the FS engine. To compensate, you'd have to use longer rods or you'd lose your compression ratio. The piston wouldn't travel far enough in the cylinder. If they're the same block, nothing changes though.

edit: the FP probably has longer rods to begin with, but what I meant was even longer than stock FP rods, if the block was taller.

The FS and FP share the same block I believe...The rods are different, because of the stroke, and the pistons can get confusing...From what I remember, the FS-ZE pistons make a ~9.1:1 Static CR in the FP, thus they are used stock...That may be different, Ed knows all the little technicalities between the two engines....I know very little about the FP...I don't know if it even has the same crank...But I think it uses shorter rods than the FS, with higher compression pistons relative to the FS (they are the same bore as the FS's, and when used in the destroked FP they make roughly the same CR)

 

[Gen1GT]

First I want to say how impressed I am with these NA threads we have. Lots of good information, lots of good questions being asked, and lots of good answers. (headbang)

Here's a couple of useful sites for you guys, in case you don't have them yet.

http://members.aol.com/FE3N/rods.html

http://members.aol.com/solomiata/MX5Engine.html

http://members.aol.com/solomiata/cams.html (this one won't help you guys much, but it's good information)
http://web2.airmail.net/theman/protegefaq/

Now, with the FP, since it's a destroked FS(or the FS is a stroked FP, whatever), I think we can make some asumptions. First, I think they share the same block, since headers will bolt up to either, and they have the same bore. The FS rods are 135.2mm with a 92mm stroke(1.47 rod ratio if you were counting, and WOW, that's really low. I was under the impression the FS had a better rod ratio than the BPs 1.56. The FE3 has a 1.74 rod ratio), and since the FP has an 85mm stroke, I'm going to assume it has a 142.5mm rod(obviously speculation, since I don't know the deck height, but they both have 9.1:1 compression). That gives it a 1.68 rod ratio, and means it'll like to rev a whole lot more.

 

[Gen1GT]

And oh ya...the FS rod ratio..that really sucks. A lot of power could be had playing with ignition timing though.....

 

[Installshield 2]

wow BP's are 1.56?...I thought they were 1.3 something...but I knew ours was 1.47...

 

[Gen1GT]

wow BP's are 1.56?...I thought they were 1.3 something...but I knew ours was 1.47...

Ya, I had all the information at my disposal, but never did the math....

B18C5s have a ratio of 1.58, so obviously rod ratio isn't all of the story. Other than high piston speeds, there's nothing saying a low rod ratio can't make lots of high RPM power.

 

[jaman]

Any clue what rod-ratio the Protege Speedworld challange cars have? I know that by the the rules they're limited to 8k rpm.

 

[Gen1GT]

Any clue what rod-ratio the Protege Speedworld challange cars have? I know that by the the rules they're limited to 8k rpm.

Not sure, but I'm sure it's close to stock. The only way to increase rod ratio while keeping the stock crank and stroke is to make a longer rod, and move the piston pin farther up inside the piston. Depending on deck height, you could increase the rod length a bit more too. 8K isn't that big of a deal for a race engine, so with a strong bottom end, here's no reason the FS can't rev that high if you're only getting 10 races out of the engine.

If I were you guys, I'd get an FP, bore it 2mm, so you'd have a 1.9. Find out if the FP head is the same as the FS. If not, flow bench them both and use the better one, and go from there......

 

[twilightprotege]

macs - did you use 9.1:1 compression? that'll be why they are a lot diff specs to mine.

 

[iluvmacs]

yes I did. I'm not going to mess with bottom end yet, although maybe I should try to design an engine from the bottom up...

 

[iluvmacs]

That kia sportage engine, with the square 86x86 bore x stroke, is for sale on ebay for less than $300

http://cgi.ebay.com/ebaymotors/ws/e...ry=33615&item=7904606793&rd=1&ssPageName=WDVW

 

[p5sundevil]

I had a curious idea before, Im sure most people have seen the recent SCC article about honda new big block conversion thats possible. Basically mating a K20A top end from an RSx with a K24 bottom end from a CRX or other K24 based car and you then have the beneficial properties of the RSX head with the cams and so forth but a 2.4 engine with the K24 bottom end. Supposedly just doing this conversion bumped the output to about 189whp, hasports blown version supposedly makes 300+ hp with very low psi.

Anyway what Im leading to is the question on if there are any engines similar enough to our to do a swap like that. I sincerely doubt it, mazda doesnt use such similar characteristics between all the engine platforms as honda does obviously but it would be a huge find for any NA guy, being able to go to such a bigger displacement engine, while maintaining the proprties of your head and getting a bonus 30-50hp out of it.

 

[iluvmacs]

I'm not aware of any interchangeability in mazda engines. I sold a civic I had for quite some time and I got used to the similarity between other cars.

All I know is that certain miata engines have a head that will fit the protege engine. That goes for the ford probe/626 as well, but I don't know of any performance or design advantage to either.