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Intake Manifold Flow Test:LS3 vs Rick Crawford Radius Rod LS3 vs Ported LS3 FAST LSXR
Here are the flow bench numbers for the cylinder head, LS3 intake + head, WS6STORE / VR ported LS3 Fast LSXR intake. I wish I'd had more intakes available for testing.
The head is placed on the flow bench and flow tested. Then the respective intake manifolds were bolted to the head and flow tested. I think the factory LS3 intake is pretty good but the WS6STORE / VR ported LS3 Fast LSXR intake.blows it away on the flow bench.
The testing took longer than expected but I think the data collected was worth the wait. The flow bench had a bearing failure with on one of the internal orifice plate if I understood correctly in the middle of the test. After the flow bench was repaired, calibrated and a "known cylinder head checked" to confirmed my testing started over from Ground Zero.
We found an interesting result and to ensure accuracy re-ran the entire series of tests to confirm the results.
All testing on SF-1020, at 28 inches with a 4.060 bore. The owner told me this SF-1020 typically reads 15-25 cfm less than the typical SF-600. Previously, many know cylinder heads that claim 300+ cfm of flow delivered ~280 cfm on this bench. Based on data collected in another set of tests this SF-1020 tends to flow very similar to another heart breaking flow bench one of my NASCAR friends used to test several sets of heads. In short, I think these flow numbers are as accurate and fairly measured as is possible for an enthusiast to acquire.
A few comments on the testing. I took a WARR 92mm TB and a pair of Nick Williams 102 TB's to also test with the intakes. The TB,'s had no effect on the flow numbers. The WARR 92mm TB bases on flow bench testing does not restrict the stock LS3 intake. Neither of the Nick Williams TB's had any effect on the WS6 / VENGEANCE Racing Ported LS3 LSXR intake. Engine dyno testing might show an effect but flow bench didn't.
No clay intake radius was used on the cylinder head. The intake port was tested bare. No pipe on exhaust.
The two gray column are RM cylinder head intake and exhaust flow in cfm
The blue column is LS3 intake & RM head, note the LS3 intake kills up to ~50 cfm of flow similar to what an LS6 intake does with cathedral heads.
The green column is the WS6/VR ported LS3 Fast LSXR intake. It reduced flow by a small amount at high lift and helps enhance low lifters flow.
The pink column shows how the WS6/VR ported LS3 Fast LSXR intake.increased or decreased flow at various lifts compared to the bare RM head.
This was the very first time I had actually saw an intake manifold match with a cylinder head so well that it enhances flow any any lift.
I did notice the cylinder head intake port sounded crisp & clean when being flow tested. Some cylinder heads have a muddy turbulent sound when they are flow tested. A cylinder head with a dirty sounding port usually isn't a very good head.
Note dyno and track testing are the ultimate measure to make judgements by not flow bench numbers. I think flow bench testing when properly done can help us evaluate parts.
Last edited by 99 Black Bird T/A; 09-16-2017 at 02:27 PM.
,,You know what's getting to me is no one has flowed a ported factory intake .. ��. I've asked Peak Performance as that's what they do and I've gotten nothing. I'm wondering how well the Peak Performance 102 would do. Because in theory it sounds good but real world data would make me fill better. I've got a factory intake and I would like to know. BTW nice data.
This is what drives me nuts about everyone saying the stock ls3 intake is as good as the fast. It's only as good on stock heads and 6500 rpm. If you're putting the stock intake on ported heads you're restricting them pretty good
If a person would only lose a few like 5 hp with a Peak Performance 102 then it's a win for the factory intake in terms of $ vs hp. That's why I want to see some listed numbers. Adding a 102 T/B can only help. If you're out there Peak Performance we'd all like numbers using Ls3 & 7 ported 102 intakes VS the aftermarket: MSD & Fast 102 intakes.
Without specific dyno / track testing - I'm speculating:
I would feel OK with the LS3 Intake on a bolt on stock displacement LS3. The LS3 intake is probably OK with a mild cam only & header upgrade if as Big Hammer mentions is a ~6500 rpm set up. Porting the LS3 might help some - like Peak Performance can do. I would like to test a Peak Performance ported LS3.
The other factor might a set of marginally ported or poorly ported LS3 heads that have an intake port that stall at say .550 lift or .600 lift might do as well with the LS3 Intake as any other intake.
A lot of it is getting a good match between the intake and cylinder head. If either is a marginal part the overall is comprised.
I think about 90% of ported heads stall before 1 inch lift. The ported heads with outstanding intake ports don't crash or become turbulent under 1 inch Lift based what I've learned over the years.
I agree with ported heads the stock LS3 intake cuts off too much air flow.
It would be good to test the stock LS3 intake with a stock LS3 head for completeness.
The stock rectangular LS3 might be about as good as a cathedral Fast but that's really apples to oranges.
Last edited by 99 Black Bird T/A; 08-01-2017 at 09:22 AM.
I sent my Rick Crawford "AirRam" LS3 intake (which adds radius rods, removes posts, etc.) to Black Bird. It routed to Rick first for some TLC to ensure it was up to snuff on his flow bench. Black Bird should have it within a few days, not sure when the additional testing will occur.
We are testing the Rick Crawford Radius Rod LS3 intake tomorrow
I appreciate Jim Muller patience with the getting the test arranged. It took a bit longer than expected.
Flow Test Data for Rick Crawford Radius Rod modified LS3 Intake
The RC RR LS3 intake tested has been on Jim Muller's car since about 2014. Jim pulled the manifold cleaned it, then shipped it to Rick Crawford to ensure everything was in order. Rick replaced an epoxy seal in the floor of the intake and shipped it to me.
I planned to test Darth 's BBK on a cathedral head and another cathedral intake on a LPE GMPP head along with the RC RR LS3 on the Reher-Morrison LS3 head.
Then an unexpected twist occurred : Sports Car Club of America and the Indianapolis Speedway decided to change and relax qualifying for this year's main event. Suddenly every racer in the area needed last minute tweaks to their car. The fast dependable shop I use for testing suddenly became buried in last minute work.
That combined with R&D for development of a less than 260 cc port head that flows ~400 cfm for a hard core customer kept them from being able to do the intake test as quickly as desired.
In short with Jim's patience, me heading to shop at 5 am this morning and the shop owner coming in early just for this test we have some interesting data to share with the community!
Getting ready to base line the head to ensure results are accurate.
The Reher-Morrison LS3 head was rechecked with the same conditions as prior tests. The results were with in 1-2 cfm of the prior tests.
The forth column medium blue color one is the Rick Crawford Radius Rod modified LS3 Intake.
Note the Rick Crawford Radius Rod modified LS3 Intake 30cfm better than a stock LS3 and roughly flows within 5-10 cfm of my VR ported Fast LSXR LS3 intake!!!
Last edited by 99 Black Bird T/A; 09-16-2017 at 02:13 PM.
Wade - Thanks for waking up at the *** of dawn to meet the shop's schedule. I felt bad that you had to be there at 7am, I didn't realize it also took you two hours to reach the shop.
Rick's version is very respectable, flowing within 3% of the VR ported LSXR across the RPM range. Obviously you lose some benefits with any OEM version...such as the ability to swap runner lengths like you can on the LSXR, and the LSXR has a 5.1l plenum (I think?) vs the OEM 3.7l plenum, but I don't know how the plenum would affect real world performance. When I bought the intake from Rick in November 2013, they were $300 plus shipping. Plus a refundable $250 core charge when you return your stock intake. If one needs the benefits of the LSXR or the last few % of performance then like anything you gotta pay to play.
Here's a link showing the stock LSXR short/mid/long engine dyno. Looks like the long runner is most desirable unless you spend a lot of time above 6500.
Thank you Hopefully, we will get to test Darth ' s BBK intake in a couple of weeks.
Next weekend is my TA's 416 install. I wish we could install both intakes on the 416 and dyno them back to back. I think the numbers would be very close since my 416 will be cam'd to peak around ~6500 rpm or so.
Honestly, I think the Rick Crawford Radius Rod LS3 intake looks like a fantastic Mod of the money!
I sent this thread to Rick, perhaps he'll have time to answer soon. Or you can PM at 'G8-4-speed'.
I have the intake on a 416 with a F1 pushing 23-24 lbs of boost....Definitely a lot stronger than a FAST. All the FAST manifolds that were on customers cars with 12+ psi had broken/split runner.
The problem with the FAST flow gains is they are at the expense of cross section and runner taper. The intake cost more power than it makes since it kills more velocity(energy) in the runners than it can make up with flow. Haven't seen anything from a 434 to a 364 not pick up over a FAST at the track or dyno so don't think motor size will fix how it works. We can argue theory but it's been easier to prove it....
I find this thread very interesting as I'm trying to chose between the Rick Crawford and Fast on my car. I have the Tick stage 2 cam 229/244 and stock LS3 heads for now
I find this thread very interesting as I'm trying to chose between the Rick Crawford and Fast on my car. I have the Tick stage 2 cam 229/244 and stock LS3 heads for now
G8 - 4 Speed makes an couple of excellent points. I would pick the Rick Crawford Radius Rod modified LS3 Intake for your LS3 and currently cam for all the reasons listed above.
If you go solid roller cam and 7000 - 7500 rpm a mid length runners fast might be worth it.
07-31-2017, 08:43 PM
Intake Manifold Flow Test:LS3 vs Rick Crawford Radius Rod LS3 vs Ported LS3 FAST LSXR 
Hopefully, we will get to test Darth ' s BBK intake in a couple of weeks.
