|
Originally Posted by SB
(Post 4712725)
Yup. The Diamond Performace/KE Thunder-N-Lightning have 1 3/4"x 34" pirmary runners. Collectors are 4" and you make the collector length.:)Collector length starts on the Diamond marine/KE's where from where tail bolts to manifold and then ends on outside end of transom exhaust tip., Most marine 502's-540's want 18-20"collector lengths.
http://www.diamondperformanceparts.c...age=1&featured See Diamond Marine pic under this dimension info. Here is Pipemax on a 502 i entered with a Crane 741 cam and 5800rpm max rpmpower. --- Single Primary Pipe Specs --- for 502.176 CID from 3800 to 6300 RPM Diameter= 1.899 to 2.024 Length= 33.7 to 36.7 inches long --- 2-Step Primary Pipe Specs --- 1st Dia. inches= 1.899 Length= 16.9 to 18.4 2nd Dia. inches= 2.024 Length= 16.9 to 18.4 --- 3-Step Primary Pipe Specs --- 1st Dia. inches= 1.899 Length= 16.9 to 18.4 2nd Dia. inches= 2.024 Length= 8.4 to 9.2 3rd Dia. inches= 2.149 Length= 8.4 to 9.2 --- Header Collector Specs (Conventional Straight Tube) --- Diameter= 3.466 to 3.716 Tuned Lengths= 19.4 best and also 9.7 or 38.8 --- Header Collector Specs (Megaphone or Diffuser Cone Shape) --- Diameter= 2.966 taper to 3.966 Megaphone/Diffuser Length= 19.4 inches Best HP/TQ Tuned Collector Lengths= 19.4 , 38.8 , 77.6 , 155.2 inches long Worst HP/TQ Loss Collector Lengths= 29.1 , 58.2 , 116.4 , 232.8 inches long Note-> all Pipe Diameters are OD and based-off .0625 inch Pipe thickness ---- Primary Pipe's Harmonics ---- 1st Harmonic = 149.4 inches long ... typically never used 2nd Harmonic = 56.5 inches long ... longest recommended 3rd Harmonic = 33.7 inches long ... highly recommended , best Torque Curve 4th Harmonic = 23.4 inches long ... shortest recommended 5th Harmonic = 17.5 inches long ... typically never used 6th Harmonic = 13.8 inches long ... typically never used 7th Harmonic = 11.1 inches long ... typically never used 8th Harmonic = 9.2 inches long ... typically never used ---- Collector's Harmonics (includes Intermediate, Muffler , TailPipe) ---- 1st Harmonic = 155.2 inches long ... longest with Mufflers and TailPipes Note: Worst = 116.4 inches long for HP/TQ Loss 2nd Harmonic = 77.6 inches long ... longest recommended with Mufflers Note: Worst = 58.2 inches long for HP/TQ Loss 3rd Harmonic = 38.8 inches long ... more bottom-end Torque Note: Worst = 29.1 inches long for HP/TQ Loss 4th Harmonic = 19.4 inches long ... highly recommended , best Torque Curve 5th Harmonic = 9.7 inches long ... reduced Torque , more top-end HP sometimes 6th Harmonic = 4.9 inches long ... reduced Torque , not recommended https://cimg5.ibsrv.net/gimg/www.off...c79bdce6ca.jpg |
There's hope
For the engine above: "Best HP/TQ Tuned Collector Lengths= 19.4 , 38.8 , 77.6 , 155.2 inches long" |
Originally Posted by articfriends
(Post 4712905)
E85, going to build one and dyno it to see IF i can get the BSFC reasonable with the compression increase. My theory is, a 500 efi on my dyno is at about .580 at wot, most whippled 2.3/3.3 93 octane motors i dyno head towards .680 on top. IF i can build a compression motor that has bsfcs in the .450 range on 105 gas and bsfcs in the .620 to..650 range on e85, the range of my boat won't really be much less than if I went with whipples. We'll see!
Ive seen some claims that 100LL is guaranteed 100+, so it’s typically higher. And the fact that there’s no lead means that if you add some, it’s jumps up significantly. Unfortunately octane testing is expensive. |
Originally Posted by Tinkerer
(Post 4712815)
smitty - does anyone make a manifold like that for a tall deck. I have EFI and would love to go to a tunnel ram style manifold. I am going to try adding twin turbos this winter and I think that would work great and look good also.
https://www.profilerperformance.com/...unnel-ram.html |
Thanks
I looked at that before I decided to go EFI. I need a manifold that allows me to do sequential port injection. |
Originally Posted by Tinkerer
(Post 4712947)
Thanks
I looked at that before I decided to go EFI. I need a manifold that allows me to do sequential port injection. https://www.edelbrock.com/fuel-rail-...nish-3659.html If you don’t want to have any welding and machining done. |
Lot of good information here.
On the original post where CMI's were mentioned, were you looking at full-length CMI's or E-Tops? If you were considering E-tops I would point you in a different direction and over to the Stainless Marine Gen II's. Minimal power difference from the E-top to the Gen II and a LOT more longevity. I've seen too many tailpipe failures over the years with EMI's. You can also get the SM taippipes stepped to full 4 1/2" if you want to make a little extra power. If you're talking full-length headers, go with Diamon's Thunder n Lightning hands down. CMI's are too leak/failure prone from my experience. They look great but 7-10 yrs from now you could be chasing issues. I have customers, myself included, with all of the above listed exhaust systems and by far everyone has been most satisfied with Stainless Marine II / III and Thunder n Lightning. |
Originally Posted by Panther
(Post 4713077)
Lot of good information here.
On the original post where CMI's were mentioned, were you looking at full-length CMI's or E-Tops? If you were considering E-tops I would point you in a different direction and over to the Stainless Marine Gen II's. Minimal power difference from the E-top to the Gen II and a LOT more longevity. I've seen too many tailpipe failures over the years with EMI's. You can also get the SM taippipes stepped to full 4 1/2" if you want to make a little extra power. If you're talking full-length headers, go with Diamon's Thunder n Lightning hands down. CMI's are too leak/failure prone from my experience. They look great but 7-10 yrs from now you could be chasing issues. I have customers, myself included, with all of the above listed exhaust systems and by far everyone has been most satisfied with Stainless Marine II / III and Thunder n Lightning. |
https://cimg5.ibsrv.net/gimg/www.off...b12892d957.jpg
https://cimg7.ibsrv.net/gimg/www.off...1365aa8691.jpg 565 cu in. Using harden marine replacement header for the gils. Original tails no reversion. These were 525 efi clones, our biggest hp gain came with the intakes. My suggestion would be go at least 540 cu in and if possible 565. |
https://cimg3.ibsrv.net/gimg/www.off...8a39891d58.jpg
They were dynoed full dress with the wet exhaust. |
| All times are GMT -5. The time now is 06:44 PM. |
Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.