Achieving 200 NA whp without a lot of $$$ or parts - Honda Prelude Forum

camarokiller · 04-21-2010, 10:39 PM

Well it's been a long time since I've logged in to the old PO.com and I'm hoping people still read threads in this forum. I'm going to work on the prelude again, but I'm doing things differently this time. I've stripped off all the worthless crap parts I used to think were cool when I was in my early 20s (spoon reservoir covers, mugen fan switches, magnacore ignition parts, other worthless crap, etc.)

What I WANT to do is build a prelude that makes 200 NA whp with no engine work (no cams, valves, valve jobs, porting, pistons, etc.) I know it's possible and I think I've got a well researched parts list put together, but I want to make sure I don't have things wrong before I get started. Most of the below parts I already own, but I'm very willing to change up the parts list to meet the goal.

Intake: Type S with K/N filter
TB: 68mm (tapered down to what size? Haven't bought this yet.)
IM: Euro R (I've read it should be port matched to the TB with a slight amount of miss-match, not sure how important that really is though. Haven't bought this yet.)
IM Insulator Gasket: Hondata (not sure if it really helps but I've got one)
Head: Shaved (how much is the real question, it is street driven 99% of the time. Haven't bought this yet.)
Header: Hytech knock off with 2.5 collector (Private Label sold on PO.com last year) with ceramic coating by Performance Coatings
Cat: Vibrant 2.5" SS race cat
Exhaust: Custom 2.5" madral bent w/ Magnaflow mufflers
Tuning: NepTune RTP demon and Wideband kit (Haven't bought this yet.)
Underdrive Pullies: AEM (been on the car forever, couldn't hurt to leave them there at this point)

I can't think of anything I've left out, but PLEASE tell me now before I start this. All suggestions are welcome, I'm all ears. Thanks!

TJ97SH · 04-22-2010, 12:17 PM

Personally I think this is a very, very hard thing to do without doing any internal modifications. I am working on getting my engine up and running after a rebuild and am hoping to get close to 175-180 HP to the wheels. I have similar modifications but also have Type S cams and pistons. (Modifications include: 3 angle valve job, slightly milled head, Type S cams, pistons, and intake with K&N, port & polish intake manifold, greddy cat back. Parts in the works: Dual Blacktrax IM spacers, insulated intake manifold gasket, Private Label Mfg. Tri-Y header, 2.5" full exhaust including Hi-flow cat)

I think it would be wise of you to do some more internal work if you are going to have the head off to have it milled anyways. If you get it shaved, they will have to take it apart and clean it up and put it back together - so you might as well have a p&p done and put in some different camshafts and maybe a valve job and new valvetrain.

With that stuff, you will definitely be able to acheive around 200 whp.

Mike95lude · 04-23-2010, 02:39 PM

I think it can be done, but I would go with a 3" cat and cat-back exhaust. You're on the right track, I use the same Vibrant Race cat, but 3" diameter myself. Neptune RTP w/ Demon is a great choice also. You could also consider going to a larger TB, 66 or 68mm would be good.

Mike95lude · 04-23-2010, 02:43 PM

Are you sure you want to go to the trouble of shaving the head and just stopping there?
You might want to consider getting adjustable cam gears. There are probably some gains to be had with stock cams too.

camarokiller · 04-23-2010, 05:28 PM

Quote:

Originally Posted by Mike95lude

I think it can be done, but I would go with a 3" cat and cat-back exhaust. You're on the right track, I use the same Vibrant Race cat, but 3" diameter myself. Neptune RTP w/ Demon is a great choice also. You could also consider going to a larger TB, 66 or 68mm would be good.

Thanks for the feedback. For the TB size, I figured if a prelude with 200hp uses a 60mm TB and an S2000 making 240hp uses a 62mm, a 64mm should be plenty. If I go bigger than that I might actually slow the velocity of intake air into the chamber, and could actually start hurting the powerband instead or helping it. Same string of logic used on the size of the exhaust, velocity is very important and if you go too big you slow the velocity causing power-robbing back pressure. Not that I think 3 inches is too big, I think anything between 2.5 and 3.0 should work fine. Let me know if my logic is sound on this.

camarokiller · 04-23-2010, 05:30 PM

Quote:

Originally Posted by Mike95lude

Are you sure you want to go to the trouble of shaving the head and just stopping there?
You might want to consider getting adjustable cam gears. There are probably some gains to be had with stock cams too.

My goal is to have the best hp numbers with the shortest parts list. That might sound stupid, but I think it's cool.

Mike95lude · 04-28-2010, 03:18 PM

Quote:

Originally Posted by camarokiller

My goal is to have the best hp numbers with the shortest parts list. That might sound stupid, but I think it's cool.

I would recommend consdering going with a thinner head gasket too, since it is not irreversable like milling the head is. It's been proven that 3" exhausts will make better power compared to 2.5" on the H22. So if you really want everything you can get out of your setup, I would go 3". Not to say that you can't get 200whp NA with 2.5", because you still could.

TJ97SH · 04-28-2010, 04:04 PM

Quote:

Originally Posted by Mike95lude

I would recommend consdering going with a thinner head gasket too, since it is not irreversable like milling the head is. It's been proven that 3" exhausts will make better power compared to 2.5" on the H22. So if you really want everything you can get out of your setup, I would go 3". Not to say that you can't get 200whp NA with 2.5", because you still could.

I am currently searching for a replacement head gasket. I was thinking about getting a thinner than stock one, but couldn't find any for the H22a4 (or a1 for that matter) that looked decent. The only ones I found were on eBay and were basically no-name brand. Do you have any recommendations on where to get a thinner head gasket?

camarokiller · 04-28-2010, 04:25 PM

The thinner gasket sounds great but I'd be worried about reliability. Doesn't this increase the chance of a leak or am I worrying about nothing? Also, what are the real-world benefits (how much of a compression and hp bump can I expect?) Thanks.

Mike95lude · 04-28-2010, 06:00 PM

Cometic should be able to do a thinner gasket and we could get you a good deal on one if you need.

Their catalog lists the .027" thick gasket as the thinnest one for the H22A4. The stock gasket is .030" thick. That probably won't help compression a whole lot, but they might be able to do a thinner gasket than the .027". I can ask if interested.

To be honest, I don't have enough experience to know at what point you risk running into sealing issues and leaks when going with a thinner gasket. I can ask about this as well, if interested.

TJ97SH · 04-28-2010, 07:17 PM

I would be interested in this information for sure. I did see that they make the 0.027" gasket, but I didn't think that would be worth the almost double cost of the OEM Honda gasket.

I will send you a PM so we don't get too off topic for this thread.

vansprinkle · 04-30-2010, 08:17 AM

there are several people on honda-tech that have taken a new oem head gasket and simply removed the middle layer, turning it into a 2 layer gasket. do a quick search on there and see if that is a route you would consider going. a lot of people actually claim that the Spoon head gasket is simply a stock one with only 2 of the 3 layers.

sakman84 · 04-30-2010, 03:49 PM

200WHP according to who's dyno? This is a lofty goal without a cam. Your going to need a tune aswell, I mean a real tune using p28ECU or something of the sorts no BS VAFC andf the likes of that. Believe me I have been down this road ur going to need to open that engine up. bolt ons are not going to do it.

This is my dyno run

YouTube - 1998 Prelude SH dyno run H22a4

. Mine made 200WHP and I had a fairly aggressive street/strip CAM stage 2 BC.

camarokiller · 04-30-2010, 04:35 PM

Quote:

Originally Posted by sakman84

200WHP according to who's dyno? This is a lofty goal without a cam. Your going to need a tune aswell, I mean a real tune using p28ECU or something of the sorts no BS VAFC andf the likes of that. Believe me I have been down this road ur going to need to open that engine up. bolt ons are not going to do it.

This is my dyno run YouTube - 1998 Prelude SH dyno run H22a4. Mine made 200WHP and I had a fairly aggressive street/strip CAM stage 2 BC.

Thanks Sakman, and I will take that as a challenge! 71dsp hit over 200whp NA with no head or block modifications beyond the milling or thinner gasket previously mentioned, however he had to remove several components that I'm just not willing to part with. I refuse to lose my AC or PS, but as a last resort I may try removing the balancer shaft. If it nets another 2 hp it may be worth it, but it's probably a waste of time. As for tuning, the Neptune RTP Demon gets an awful lot of praise, so I feel it's a wise AND economical choice.

At this point I'm still trying to nail down the specifics of the TB (opening size tapered down to what size on the IM side.) Only thing I had planned to do to the Euro R IM is plug the EGR port and port match to the TB. The skunk2 IM is suppose to get just slightly better top end, but it's hard to sacrifice all that great midrange power the Euro R makes.

Any other suggestions you have that doesn't include cams, porting, or block work, I'm all ears!

sakman84 · 04-30-2010, 05:01 PM

As you said 71DSP removed some components most of us would never part with, I think all of us here are talking about making 200WHP without taking such measures.

My post sounded like I was knocking your choice in NEPTUNE, my intention was the opposite. NEPTUNE is great. My purpose was to say stay away from VAFC and crap like that. Your wise to use NEPTUNE.

I would not bother with removing balancer shaft, I dont see the real benifits in doing that.

EURO R manifold is also a good choice. I wish I had underdrive pulleys on mine! They are so worth it, I just could not get a hold of any.

Glad your taking up the challenge as so many of us have done. Have fun with it that is the whole point of building cars right? Just keep it in perspective a real world 200WHP number from a good dyno (not a read high make u feel good dyno) is a big proposition. Personally I dnt think it can be done with those parts you listed, all thought they are excellent parts in themselves.

With an unlimited budget and some seriously expensive parts and lots of tunning maybe 200WHP is possible without internals but I honestly doubt it.

UAludes · 04-30-2010, 09:28 PM

im making 197hp with no internal upgrades! And i had a aem long ram intake before now i got the V2 so idk if that changed anything!

You Tube

indylude18 · 04-30-2010, 09:39 PM

^That number is bs. The only number that counts for anything is wheel hp, not some guesstimate of crank hp.

UAludes · 04-30-2010, 10:03 PM

my wheel hp is posted did you not see it my engine is making 197hp

indylude18 · 04-30-2010, 10:20 PM

You are making 175whp/136tq according to your lil video.

Unless you pulled the engine to run on a dyno outside the car to measure the crank horsepower, that 197 number is just a guess.

camarokiller · 05-01-2010, 12:04 AM

Quote:

Originally Posted by UAludes

my wheel hp is posted did you not see it my engine is making 197hp

Sorry dude, we're talking whp. To get 197whp you'd have to be doing better than 245 at the crank.