CorvetteZ51Racer

For those who have been wondering how the porting job went on ZRRacer's 113s, the flow numbers are as follows (all numbers on a SuperFlow 600 bench @ 28" H2O):

Intake:
0.200" - 136.5
0.300" - 184
0.400" - 217
0.450" - 229
0.500" - 239
0.550" - 245
0.600" - 250
0.650" - 251

Exhaust:
0.200" - 110
0.300" - 134
0.400" - 168
0.450" - 182.5
0.500" - 192
0.550" - 198.5
0.600" - 200
0.650" - 201.5

FYI, the reason I flowed the heads to 0.650" lift is due to the high lift flow stability of the heads. While doing the machine work down at the shop, the heads have been machined to accept up to 0.620" lift. I don't have the pictures downloaded from my camera yet, but those will be coming along with (maybe) dyno numbers (the car's getting dyno-tuned friday, but it's up to Robin if he wants the numbers posted).

65Z01

Those are very nice numbers and the Exh/Int is very close to the "magic" number of 80%.

Did you use 2.00/1.56 valves & pocket port only or did they also unshroud the intake and enlarge the ports?

CorvetteZ51Racer

I'm assembling the heads and installing them tomorrow with the following:

FULL port and polish (bowl blend, short side radius work, push rod slot wall moved (still able to use standard rockers and lifters)

Combustion chamber reshaping, including valve unshrouding and reshaping of chamber to "fast-burn" style chamber

LT4 valves
Titanium retainers
Hardened valve spring seats (seat pockets cut to accept 1.470" springs, though they're not being installed until the next cam change)
All valves shimmed to within +/- 0.002" of specified 1.800" spring install height
ARP screw-in studs

I'm sure there's something else I'm forgetting....I'm going to get 5 hours of sleep tonight which is a LOT for me recently. I've been fighting these heads a LOT due to some bad core shift in the castings (should have only had to spend ~15 hours porting the heads...these have over 45 hours in them because of trying to work around the core shift). FWIW, the flow numbers are comparable to TPIS's heads, though I'm on the low end of their range due to the core shift problems. I had to reduce the work on certain ports in order to maintain an acceptable flow variation port to port, so there's more in them, I just need a set to work that doesn't have as much shift.

65Z01

Thanks for the feedback.

The reason I ask is because head port/work is on my TBD list and I've seen various flow numbers on results of such mods.

Hope you get some nice dyno results.

ZD1

great job I wouldn't expect a ported set of 113's to go beyond 230!

? What do you mean by "move" the "wall"?

W

CorvetteZ51Racer

When you look down the intake port from the manifold end, you'll see where the port comes in sharply where the pushrod goes by. I moved the inside of that sharp bend back, opening up that part of the port. I'll post some pics tonight, but I'm leaving now to go to the shop to get ready for the car's arrival for the installation.

jburnett

Those are good numbers and pretty closely back up what I've seen on my bench after working over a set of 113's... About 250 cfm before stall is about max for those heads. Great thing is they still have a fairly small runner cross-section that provides excellent velocity and swirl. I/E ratio "magic number" is actually around 70-75%; 80%+ is really good and will work tremendously well on a forced induction motor.
-Jeb

CorvetteZ51Racer

Very true. I'm on a lunch break right now before Robin shows up, and I cc'd the runners earlier this morning...178cc. With that port size, the flow numbers are very close to AFR's 180cc head, but with smaller valves (less mass, and less shrouding at low lift).

HeaderDesign.com

I have been wondering how the port job went on ZRRacer's heads. Very good job! I was hoping to see the intake flow go above 250CFM. I thought I was going to be working on this project, but I guess Robin fired me. I had already set up most of the analysis files, so maybe you could tell me the final port choke cross-sectional areas so I can plug 'em in.

Since I suppose you want some feedback, I'll give you a little. First, you should measure the flow at 0.050" and 0.100" valve lifts. I don't like to have to assume these values since they have an influence on the optimal lobe centerline angles, and sometimes will influence the decision in lobe selection if two lobes are close to optimal. Alot of the good and bad things that happen during overlap occur at those valve lifts, and the early part of blowdown, when pressure differential is the greatest, occurs at low valve lift.

The exhaust port flow is quite high at high lift. I would generally work step-by-step with the head porter on a restricted induction engine like this to make sure that the ideal flow bias is reached. Correct flow bias for a street performace L98 would be like 70-72%, and maybe a little higher for Robin's engine once it is cammed out. The basic porting procedure is to maximize low-lift exhaust flow while leaving the exhaust port cross-sectional area the same. Then go to the intake and port it. An analysis is then run to see if the exhaust port needs to be further modified. If you go too far on the high-lift exhaust flow, you will hurt the low-lift. The available cam lobes are poor at correcting this situation. I wish someone would produce some good solid roller exhaust series.

For good low-lift port flow, differentiate the flow curve to see that it is negatively sloped everywhere. A good target is to have the 0.1" flow 57% of the .2", and the 0.05" flow 57% of the .1" flow. For good non-restricted designs like the AFR's, the flow curve will be linear through low and mid-lift. Shrouded or poor designs will have a sag.

Good luck with the rest of the project. You are off to a great start. I hope you drank a few of these :cheers: during 40+ hours of porting.

DieL

My engine builder said LT4 valves are way too fat. .. lose some flow.

CorvetteZ51Racer

We may have lost some flow, but we dropped 29 grams off of the intake valve and I don't remember how much off of the exhaust valve. This will allow us to run a lighter valve spring (once the rest of the engine is built to match the heads) which will reduce parasitic losses. Also, the use of the sodium-filled exhaust valve allows us to bump the compression up a little bit more than would have otherwise been possible. The slight loss in flow isn't really that big of a deal on this motor because class rules require the use of the stock TPI intake, which makes the intake manifold, not the heads the restriction. That's also one of the reasons I went for as much low lift flow as I could get without sacrificing high lift flow stability (notice the flow stays nearly constant as it reaches the flow peak...it doesn't peak and then fall off).

HeaderDesign, I think that one of the reasons why Robin came to me to do these heads and the rest of the motor is because I do research on Winston Cup (or is it Nextel Championship now... :troll ) restrictor plate motors, specifically focusing on the intake and valvetrain side of things. The main thing I'm not crazy about with this project is that the short block stayed in the car, and the ECM is getting tuned on a DynoJet. If time and desire had permitted, I would've liked to have yanked the whole motor and set it up on our engine dyno so that part throttle as well as WOT could be tuned in the ECM. After all, road racing engines don't always run WOT. I'm pretty sure we're going to do that when the new motor gets built. Anyway, off to bed. I'm currently staring less than 4 hours of sleep in the face tonight, with more work to do on the car in the morning (I guess that would be later on this morning). I will definitely be drinking *ahem* one or two :cheers: once everything's finished up tomorrow.

88BlackZ-51

never did hear what the outcome was of the 113's? what kind of gains did u see etc......

MrNuke

Pretty good for stock 113's, but how much did the porting and everything cost?

HeeHaw89

Looks like 45 hours on them...Could possibly be several grand I would think unless there was an agreement or something on the price.

comp

45 hrs

Corvette0096

They flow almost the same as my protoplines out of the box.

180cc

http://members.aol.com/jsc41098/flow

Corvette0096

They flow almost the same as my protoplines out of the box.

180cc