anybody use this one from ebay https://www.ebay.com/itm/FOR-CHEVY-S...4234%7Ciid%3A1

 

Looks like a Super Auto see posts starting at post 458

Haven't had one on an engine but it did very well for a 78mm snout intake on the Flow bench. Sort like a baby LSXRT

 

Sounds like a nicely set up Z06

The ported plastic intakes I've seen don't take it quiet that far. If there's about 2mm of material the Dorman's I've seen probably left about half of that. However, I'm not up to speed on what the best way to port a Dorman LS2 really is. WS6Store ported several Dorman LS2's for the test and might be able to help. Likewise HioSSilver has done some really nice porting and might be able to help with specifics.

 

Thank you sir. It runs well...pretty standard setup. It's a DD and local autocross toy.

I got with HioSSilver and he made a comment about ports aren't technically centered. I also came across a TY video showing this issue (notice the maker of the YT video lol):

So my plan is to investigate this and do some layouts and see how the ports line up.

 

Excellent video thank you for sharing! That's excellent info to have in the thread. Please share what you find researching.

 

I'd be concerned about porting the Fast 102 and not having enough wall around that gasket. I've seen pics where that thin wall has separated.

 

My plan is to look at a ported FAST 102 that a friend has to compare runner shapes/sizes at the outlet and see if I can adapt that method to the Dorman LS2. Then ideally get back on the same dyno for before/after. May be a couple of weeks.

 

Picking up the ported FAST tonight and may plug away at porting the DLS2 this weekend. Also picked up some JB weld to patch/fill/smooth areas that may need it to mimic the FAST runner design.

 

The Fast 92 had a decent gain over the Dorman LS2 in this article. CPG Nation Dorman LS2 vs Fast 78

Here's the graphs.
Looks like the Dorman LS2 held its own vs the Fast 78 under 6,000 rpm



and Dorman LS2 vs Fast LSXRT

 

If a guy was needing to buy any of the 3 manifolds, bang for the buck, DLS2 wins by a landslide.

 

Isn't that article comparing the Dorman LS2 with the Fast 78 rather than the Fast 92?

Equipped with the Dorman and tuned to perfection, the modified 5.3L produced 465.5 HP at 6,600 RPM and 412.5 lb-ft of torque at 5,300 RPM. We then replaced the Dorman with an original FAST/Wilson intake that featured the minuscule 78mm throttle opening. The OG FAST was run with the same injectors, but a much smaller 78mm Accufab throttle body. Despite the handicap in throttle body size, the FAST intake produced 471.7 HP at the same 6,600 RPM and 413.7 lb-ft of torque at 4,900

 

Yes that is absolutely correct. Dorman LS2 vs Fast 78
Fixed my typo.
Thank you.


I'd buy one of those broken bottom Fast 90's in the classifieds for $300 and a gallon of JB weld before buying another Dorman LS2.

 

Dorman ls2 is good on a budget but needs a lot of clean up in the ports

 

Which is exaclty why I bought mine new for $410 vs $800+ for a FAST. I get 90% of the HP gains compared to a FAST with the DLS2 unported. Oh....go look up the price of the DLS2 now...$700+ a year later

Agreed...I spend all day Saturday doing exactly that.

**Information below is MY findings, this is the first time doing something like this so take it with a gain of salt, however being an engineer I approached this "logically" IMO. Reduce areas where air could become stagnant/interrupted/turbulent**

Cliff notes on porting a DLS2 to a stock 243 heads:
1) DLS2 port width at the head matches that of the stock heads = not worth widening to the reported 1.1"
I had access to PORTED 243's with a port matched FAST 102 to those exact heads which DID show 1.1" head/intake port width AND that the intake porting was "angled".
2) The runner thickness at the area that needs the most removed is ~5mm. (drilled a hole and verified thickness at each runner).
3) The runners of the DLS2 and Fast102 look very similar in design/shape but the FAST has a substantial larger plenum volume (obviously hence the increased height which may allow slightly longer runners)
4) It seems like one engineer designed the upper runner half and someone else designed the lower flange half then glued them together...fairly poor transition between the two halves.
5) All said and done there was more material on the floor than I ever thought.

Hopefully soonish I can get some time to do a couple of pulls on the dyno to see what happens. Gain or lose power...I'll learn something

Ported FAST102 lower section on stock 243 heads

Drilled a hole in all runners where most material will be removed to check wall thickness

The hole ends up directly in the corner of the runner

Put drill bit back in and verified wall thickness

Final product. Removing this much material you need to be careful. The wall can get paper thin to where light will shine through the plastic. I worked my way "UP" the runner focusing on blending the large runner radius to the smaller port radius. If you wanted to go nuts and make it perfect you could also fill in some low areas but what I did was 90% there that I didn't feel the need to spend a lot more time on this. I did NOT touch the original port opening here as I felt it lined up well on stock heads. More porting may be needed once heads get ported.

Here you can see I got too carried away on this one as it was my first one...lesson learned. This shows aluminum foil tape inside the runner as a backer to keep JB weld from dropping through. I also sanded then "hatched" around all holes to let JB weld bite. Once JB weld was solid enough but still pliable, I removed the tape and smeared more JB weld over the small holes and let it fully cure.

Not pretty but functional. I'll address aesthetics later.

Hopefully this helps others smarter than me when it comes to porting/engine builds. This thread was a GREAT source of data/info. Just trying to continue the info sharing.

The next dyno session I hope to show graphs with the only changes being a Halltech CAI with stock C5Z MAF swapped out for a stock LS3 air bridge/green filter/card MAF on SD (gains of +5hp/+5tq) both with stock DLS2 intake and finally the ported DLS2 with LS3 CAI. The Halltech and LS3 runs were literally back to back same day same dyno.

 

This is from way back, but I've read where it is OK for the manifold port to be a bit smaller than the head port, as it helps to prevent reversion, though I don't know if that's an issue nowadays.

 

Smitty2919, that's a fantastic post! Thank you for sharing!

From what i understand the top and bottom of the DLS2 were designed by different people. Wilson/Fast designed the lower half for the Fast 78mm intake and Dorman licensed accordingly. The top half is a copy/based on a GM LS6 intake.

I think your porting will definitely help the manifold. Nicely done ✔

 

Thanks I hope I see something via the dyno. I wish I looked inside my LS6 intake more closely when I had it and compared the runners. Looking inside the DLS2 around the runner inlets, there seems to be areas/pockets that could be filled in with JB weld to let air flow better.

I contemplated going nuts and trying to separate the intake halves but the more I looked at it, the runners themselves would be split along the runner sides...which would be a PITA to separate. I also noticed an encased rubber gasket running the perimeter between the halves.

A realistic option MIGHT be to cut out the intake floor (and two center supports like people do on "radius rod LS3" intakes to gain access to the plenum) then rivet/JB weld and new floor back in.

If the DLS2 remains $700-$800 then it would be a tougher decision between that or the FAST 102 for others looking to buy.

 

Holy $hit, I paid less then half that for my DLS2 intake, I will see if I can find when I bought it, that's crazy!!! And I thought I was crazy paying what I paid for it.

Stampede.

 

WHOA! They went up! RockAuto lists it for about $728

 

Yup. I bought mine from RA a year ago.