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Purely out of curiosity, how different do you guys think the results for the Dorman LS6 90mm manifold would be compared to the Dorman LS2 and TPis 90mm manifold? Would it probably need porting to be competitive? More along the lines of the Peak ported 90mm manifold?
Purely out of curiosity, how different do you guys think the results for the Dorman LS6 90mm manifold would be compared to the Dorman LS2 and TPis 90mm manifold? Would it probably need porting to be competitive? More along the lines of the Peak ported 90mm manifold?
Interesting question, here's my take on it.
Can you provide a part number for Dorman LS6 90mm manifold?
Every time I've seen " 90mm LS6 Dorman" listed its the exact same manifold as the Dorman LS2 with another name slapped on it based on the Dorman part number. It's possible that's changed.
The TPiS/LPE 90mm LS6 intake easily out flowed all versions of Dorman LS2 ported or unported that I've tested so far. The results are listed in the chart.
I think it would take a lot of porting and testing to get the Dorman LS2 on par with a TPIS / LPE 90mm LS6 on the flow bench. The Dorman LS2 seems to fall off on the top end flow. On an engine dyno they might be close/closer.
I had my TPiS/LPE 90mm LS6 ported by Peak Performance but haven't had a chance to add the results to the chart. There was a slight increase in flow but my feeling is the LS6 intake runner is maxed out at about 265 to 270 cfm.
Last edited by 99 Black Bird T/A; 12-30-2018 at 07:37 AM.
Can you provide a part number for Dorman LS6 90mm manifold?
Every time I've seen " 90mm LS6 Dorman" listed its the exact same manifold as the Dorman LS2 with another name slapped on it based on the Dorman part number. It's possible that's changed.
The TPiS/LPE 90mm LS6 intake easily out flowed all versions of Dorman LS2 ported or unported that I've tested so far. The results are listed in the chart.
I think it would take a lot of Portland to get the Dorman LS2 on par with a TPIS / LPE 90mm LS6 on the flow bench. On an engine dyno they might be close.
I don't have a direct part number unfortunately, I had just seen the Dorman LS6 90 mm advertised and was curious. They may well be the same thing. From an internet search, all I could see on their website was that the 615-900 seems to be the LS6 and the 615-901 seems to be the LS2 but it's not clear if the LS6 is the 90mm version. Here is an eBay ad that details it but actually confuses it further...
I don't have a direct part number unfortunately, I had just seen the Dorman LS6 90 mm advertised and was curious. They may well be the same thing. From an internet search, all I could see on their website was that the 615-900 seems to be the LS6 and the 615-901 seems to be the LS2 but it's not clear if the LS6 is the 90mm version. Here is an eBay ad that details it but actually confuses it further...
I think that is the same Dorman LS2 intake. The add is pointing out that DLS2 can also be used on LS1/LS1 engines as an LS1/LS6 intake manifold replacement. That's definitely true. There are a few tweaks needed depending on the application like TB cable bracket etc.
The Dorman LS2 is a nice option to have available. Out of the box it flows better than the LS1, LS2 and LS6 intakes. Before Dorman got after Rock Auto on pricing the LS2 Dorman could be had for low as ~$320.
Last edited by 99 Black Bird T/A; 12-30-2018 at 08:09 AM.
Ok, you're spot on (no surprise! ), Despite being advertised in a few places as a new 90mm LS6 version, it's just the LS2 version of the Dorman. Sorry to waste people's time on this one!
Ok, you're spot on (no surprise! ), Despite being advertised in a few places as a new 90mm LS6 version, it's just the LS2 version of the Dorman. Sorry to waste people's time on this one!
No wasted time. You had an excellent question. That's what these forums are all about!
It's sort misleading some business advertise products. I'm sure other folks have wondered or will be wondering too.
This will be the last flow test data from the GMPP 243 heads in their original condition. Bret at Land Speed Cylinder Heads will have a new revised valve job for the GMPP 243's ready this month and with a bit of bowl work.
As we examined this particular set of heads in detail over time and multiple trips to the flow bench we tested some of the other ports just for kicks. We found some variation in the flow between the various ports.
By random coincidence the port I picked for the flow test turned out to be the worst flowing port of the ones we've tested. That's all well and good for giving conservative accurate flow test data for a realistic evaluation of various intake manifolds. However, my long term goal has always been to use the GMPP's. I want the heads to be more consistent in how they flow and focused on best mid-life flow. Bret at Land Speed Cylinder Heads is developing a revised valve job for the GMPP 243's this month and doing a bit of bowl work.
We will flow a couple of intakes for comparison. Probably the stock TBSS, the LSXRT, the 90 mm LS6 and possibly a couple of others.
I sent the TPiS/LPE 90mm LS6 to Peak Speed Shop for their radical porting. The last flow test on the original version of the cylinder heads is below with the Peak Ported 90mm LS6 intake. The other LS6 intake tests are included. All of these tests were done with the same LS6 intake, the one that was on my 99 TA for 15 years.
99 Black Bird T/A's LS6 intake tests.
Last edited by 99 Black Bird T/A; 01-01-2019 at 10:29 AM.
The Peak Speed Shop ported TBSS greatly benefited from Peak's clean up according to the flow test data. The 90mm LS6 didn't benefit much from the radical porting according to the flow bench. Bret carefully felt around inside the trick LS6 and felt the radical port and clean up could have been a little more aggressive but it was a decent clean up. Removing the center posts helped the plenum volume slightly.
When we saw the increased flow at .100 my heart sank. Typically flower at .100 doesn't help power much but does indicate the intake is a little more sensitive to reversion. Likewise, in my limited experience when the .100 flow number increases after port work very seldom does the high lift flow numbers increase very much. That proved true here as well with 0-2 cfm gains in the higher lifts.
I've decided not to test this intake with radius rods because I think at ~270 cfm the LS6 runner is maxed out or nearly maxed with all tweaks listed above applied. Others have reported ~265 as about the max for the LS6 runner. I think based on the test data the best mod for an LS6 intake is the 90mm snout. Porting is expensive for 0-2 cfm over .100 lift.
In ideal conditions 2 cfm peak increase might net 4.5 flywheel hp. I would expect the porting my 90mm LS6 intake to be worth 0-2 hp whp - best case.
For reference I've read the Fast 90/92 runner maxes around 278-282 cfm.
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Last edited by 99 Black Bird T/A; 01-01-2019 at 10:02 AM.
Great stuff in this thread OP. Just spent about the entire day reading this.
One question, I'm not clear on why you sent the 90mm LS6 intake to LPE. Did they do the snout install? Or something else?
Thank you, its been fun doing the flow testing and writing up the results. I'm happy it was of interest
Yes, the LS6 was sent to Lingenfelter/LPE for the 90mm snout mod. TPiS developed the mod. I'm not sure if LPE does it in house or farms it out to TPiS.
Ack! Need to update my sig line. I've been through a 2016 Stingray and I'm fixin to sale my 2017 Stingray. Moving to a 2004 C5 Corvette Coupe, hence my interest.
Gooze_01, I'm usually game for testing most types of intakes
The Mamo MSD is sweet & definitely my idea of top notch 7,000+ rpm and plan to shift at ~7,500 rpm type of intake!
If we can round up a BTR definitely willing to test.
If you go BTR shoot me a PM if you like and we can talk details if your up having your BTR tested.
Additional tests will be with the revised version, Land Speed Cylinder Heads sent me this picture today!
GMPP, heads getting some attention and love at Land Speed Cylinder Heads
Originally Posted by bigsapper
Ack! Need to update my sig line. I've been through a 2016 Stingray and I'm fixin to sale my 2017 Stingray. Moving to a 2004 C5 Corvette Coupe, hence my interest.
Definitely a couple of sweet rides!
Thinking C5 Z06 or C5 A4 or C5 M6?
The C5 Z06 is definitely one car I still want to buy one day!
Last edited by 99 Black Bird T/A; 01-02-2019 at 03:00 PM.
Sharing a few photos from Land Speed Cylinder Heads of the reworked chamber for the old GMPP's. Several CC's of material removed to hit 67 cc chambers with heads cut .030, if I recall correctly stock LS6 is 64cc. Long term plan is for a LS2 stroker.
Love the real data provided here sir. I’m of a similar OEM+ budget mindset on my Caddy V build. Looking forward to the numbers my ported Doorman LS2 puts down vs the stock LS2. Love the stealth factor and just found the right factory engine cover. Kind of hoping it hides the milled brand name on my worked heads.
Thank you 84FSP, it's been fun collecting the data.
Land Speed Cylinder Heads completed the new mid-lift valve job the GMPP heads.
While all of the testing was done on the same cylinder over the long course of testing we found one of the other cylinders that didn't flow as well. It had a nasty sound on the bench and the bowl area looked rougher. The exhaust side which isn't the focus of the intake testing had a lot of room. improvement.
Sometime late today, I should get the flow data for the revised head posted posted.
12-30-2018, 06:07 AM
), Despite being advertised in a few places as a new 90mm LS6 version, it's just the LS2 version of the Dorman. Sorry to waste people's time on this one! 
