After some thought about which way i wanted to take a motor that just burned a valve, i decided on a total rebuild. at the moment it's looking like:

ECU: 98 p73 USDM
Head: GSR ported by me
Valves: Ferrea 6000
Springs: Type R on both sides
Cams: 98 Type R
Manifold: Blox
Pistons: Mahle Forged
Rings: Mahle
Rods: stock
Crank: stock
bearings: Honda

Here's what i found when we tore into it. {yes i cleaned the outer pistons, at the time i was considering just a top end rebuild}




to those of you who have been here. helpful hints, part suggestions or anything else is very welcome.

 

the car is gonna run terrible on a stock ecu with the mixmash of parts. Go for a chipped ecu and have Ground Zero Motorsports in P-town tune it

 

check your rod bearings cause that burn vavle can put some wear on them. mostly that cylinder. im just finishing a rebuild on a 2000 gsr that i picked up for $2g cause it had a burned valve. check that seat real good cause it may have some uneven parts on it. most of the time the build up on the valve will flake off and try to exit and thats when the valve rams into that flake and breaks the valve. i would take it to a machine shop and let them check and recut the seats

 

Dear Jmar You know most engine rebuilds consist of a bearing replacement? Take a Seat

 

LOL no kidding, rebuilds and bearings. also, i totally agree on the ecu. last night i picked up a 1998 type r p73 ecu. should be the perfect map for 10:8-1 compression, a blox mani and type r cams. i say that because i'm basically building a type r motor. after looking at pistons, i've gotta tell you guys. the mahle deal looks better than any of the OEM stuff. bairly more money for a piston 40 grams lighter and far stronger. 4032 alloy is also really oil friendly. clearances can be tight. i'm praying that i don't have to spend the cash on a line hone or rod resize. if i can just buy the proper color honda bearings and pay for the bore & hone this is going to be a very inexpensive rebuild. i'm glad i listened to you horse. you pretty much talked me out of the JDM motor on my last post. besides, this new motor will be turbo friendly with the pistons and valves i'm using & be a strong ride with great MPG in the mean time.

p.s. from what i gather the GSR p72 ecu and ANY single stage inake manifold is a seriously retared idea.

 

exhaust valves on both sides, intake in the middle. as you can see, a good deal of my oil burning was on the exhaust valves. once the valves get coated with oil all sorts of fun things happen. the valves can't cool themselves and you drop compression if they can't seal. good times...

 

ooh ugly valves! but g/l on the build, you seem to have it under control

 

Well the p73 seems to be alright. But you would get some extra ponies out and a few extra MPG's on a properly tuned car. And once you chip an ECU they are all the same.

 

i thought about doing the p28 route since it would be easier for future mods. i just happend to score a great deal on the p73. for this combo it's a good ecu, i'm just limited on expansion plans with it.

 

just finished the head a couple hours ago, also weighed the valves. the ferrera 6000 valves are 5g lighter on both the intake and exhaust than the stock GSR valves. they are also stronger. amazing deal for $235 shipped. this head took around 12 hours to complete. the factory ports are actually really good so there isn't a lot of material that needs to be removed.

 

looking good so far!

 

What's your throat to valve ratio?

 

got me, i doubt it's far from stock. in fact, where do you measure this throat in the ratio and why is it an important measurement? like what use does it provide? what i do know is that i'm heading to the machine shop in a minute. after the new guides & valves are installed i'll get flow numbers on the head & we can see how much it picked up over stock. the 3 main things that have been done to this head are: casting flaws removed, short turn radius smoothed, and the dividers have been knife edged. i'm also cleaning up the blox manifold {probably should have bought an edelbrock} since it's a bit rough. i still can't figure out why the skunk and blox use the b16 port exit. the p72 uses a taller injector hump. at any rate i'm happy with a 40% plenum increase over stock and a shorter runner. i'm also ditching the type r cam plan. the blox type A or crower 63401 are bairly more money than a used set of R's and they should make a couple more HP.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by idrivesideways &raquo;</TD></TR><TR><TD CLASS="quote">got me, i doubt it's far from stock. in fact, where do you measure this throat in the ratio and why is it an important measurement? like what use does it provide? what i do know is that i'm heading to the machine shop in a minute. after the new guides & valves are installed i'll get flow numbers on the head & we can see how much it picked up over stock. the 3 main things that have been done to this head are: casting flaws removed, short turn radius smoothed, and the dividers have been knife edged. i'm also cleaning up the blox manifold {probably should have bought an edelbrock} since it's a bit rough. i still can't figure out why the skunk and blox use the b16 port exit. the p72 uses a taller injector hump. at any rate i'm happy with a 40% plenum increase over stock and a shorter runner. i'm also ditching the type r cam plan. the blox type A or crower 63401 are bairly more money than a used set of R's and they should make a couple more HP. </TD></TR></TABLE>

I'm not a pro head porter but the few that I've communicated with taught me that throat to valve ratio is very important. It should be around .85-.9 depending on the build. Meaning throat I.D. should be aroung 85-90% the O.D. of the valve. If it's too large, you lose velocity, hurt performance and the head will make less power than stock. The throat should be measured before removing any material, as the throat is usually already pretty close to the .85 mark. Somethimes porters won't even remove material, it's not about how much material you remove, but where you remove it.

Did you get the head flow benched before the port work to establish a baseline?

 

ah, now i know what you mean. yes the valve job that's being done is going to be 1st rate. hutchins performance engines is doing all the work. the owner actually builds comp eliminator motors that you see bracket racing on ESPN. he's done a few hondas as well. as you can see in the above picture, the valve seat is flush with the casting. that's about as close to ideal as a home job is going to get. there is no turbulance from a rough edge of the seat and the finish has a slight swirl to it. when the valves and seats are cut it will round out into the seat area and do away with the straight edge that you see from the factory. my whole goal with this build is to see how much HP i can get out of a CTR-ish profile cam and still keep respectible MPG. i'm using a P73 ecu so i don't want to stray too far from a type-r build. it's not the most aggressive map for my combo but it should be a safe one for that tank of bad gas i'm bound to get and also provide good MPG with the stock 24lb injectors. i actually need to ohm test a set of ford SVO cobra injectors i have laying around. they are the same flow rate as ours, same clip as well. if the ohms check i might just use those since they are newer.

 

Here's a pretty good explaination of what I'm talking about.

http://www.tmossporting.com/ta....aspx

I researched and communicated with several professional porters for about a month before I even practiced on several junk heads, let alone on a head I planed on using.


Modified by ruffrhyder at 9:17 PM 8/19/2008

 

very good stuff. also very applicable to the factory pushrod v-8 castings. many have major room for improvement. the p72 head on the other hand, is really good out of the box. i didn't reshape anything & concentrated on bringing in the short turn radius and blending the bowls. the valve job is one area you can improve flow. if nothing else, people really can pick up power with a good valve and real valve job. the stock 1 angle blows goats backwards.

 

where did you get your pistons from?

 

summit racing price matched MAW products. i bought the 81.25 version of these

http://cgi.ebay.com/ebaymotors...ZWD1V

 

Who's machining the rods to run the forged pistons?

 

see above post on who's building the motor.

is there something specific you know about this piston and the GSR rods? to the best of my knowledge the old pistons pop off and the new ones go on. the rods are being resized on the big end due to ARP bolts going in. rod bolts are the one place i did not want to re use the old ones.

i guess i don't understand the refrence to "forged pistons" and machining rods? the clearance for any piston is listed in its spec sheet. the engine builder or machine shop will then do the bore and hone accordingly. ring end gap is filed and you're good to go. as far as hanging pistons, almost any engine shop can do that task.


Modified by idrivesideways at 11:08 PM 8/24/2008

 

sending the injectors off today as well. one of the guys on corvetteforum turned me on to this place. http://fuelinjectorconnection.com/ they offer flow balancing, cleaning and also high performance injectors. ahh.,..later on my cams, springs and pistons should be here i can't wait to get this thing back on the road.