Velocity stack testing!, Been playing on the dyno again! |
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Velocity stack testing!, Been playing on the dyno again! |
Jake Raby |
Nov 9 2004, 04:29 PM
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#1
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Yep,
Remember the posts about URY and his "too tall" stacks?? I decided to post the data from my latest engine combo as i try to find the perfect stack arrangement for it.. Guys wanting a cheaper, reliable TIV engine will love this one because it has a ton of torque and awesome smoothness. It does NOT have ported heads, so its almost 1,000.00 cheaper than some of its bigger brothers and makes torque very similar, but does not have the RPM range.. Ultimate daily drivin, short shiftin, 901 abusin power- plant.. Anyway, look at these plots and descriptions for this engine here http://www.shoptalkforums.com/viewtopic.php?t=80579 I plan on replicating this exact test on the next 10 engines I dyno and see how port work and cam changes effect the results. The results from this engine do not follow suite with my earlier findings, but almost all those tests were done on high revvin engines.... |
Root_Werks |
Nov 9 2004, 04:36 PM
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#2
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Village Idiot Group: Members Posts: 8,338 Joined: 25-May 04 From: About 5NM from Canada Member No.: 2,105 Region Association: Pacific Northwest |
Wow, the 6" stacks are sort of a wierd curve? (IMG:style_emoticons/default/wacko.gif) I like the results on the 2.65's though! Cool stuff Jake! (IMG:style_emoticons/default/clap56.gif)
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Jake Raby |
Nov 9 2004, 04:43 PM
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#3
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Thanks!
Yep, the 6" stacks are all over the place.... Thats what i have seen before, but typically they make a bigger impact up top in the powerband and hurt power more there. My guess is that these test progress to higher tuned engines I will yet again see this. This engine has a slow piston speed, and high velocity heads with a huge split in the duration between intake and exhaust on the cam. The tuning is effecting my results with this one, but thats why I'm doing more of them back to back. The tests are fast and easy because it only takes a few minutes to swap them out and unless they effect jetting no other changes are made.. |
Root_Werks |
Nov 9 2004, 04:49 PM
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#4
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Village Idiot Group: Members Posts: 8,338 Joined: 25-May 04 From: About 5NM from Canada Member No.: 2,105 Region Association: Pacific Northwest |
One of my costomers with a 1750 356 and 44's will like to hear about this. Thanks again. This sort of testing rocks! (IMG:style_emoticons/default/mueba.gif) (IMG:style_emoticons/default/aktion035.gif)
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Jake Raby |
Nov 9 2004, 04:51 PM
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#5
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
The 356 is a totally different world...
The best stacks I ever found for them were around 3" tall... |
URY914 |
Nov 9 2004, 07:27 PM
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#6
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I built the lightest 914 in the history of mankind. Group: Members Posts: 121,115 Joined: 3-February 03 From: Jacksonville, FL Member No.: 222 Region Association: None |
Jake,
About a month ago I took your advice and changed my 6" to 1-7/8" from Aircooled.net. And I reinstalled the K&N filters. Do I feel a change?...not really, but my engine needs a overhaul anyway. I'm glad I was able to spark your interest in doing these tests. Once again you come through with real world, tested, and verified info. Now can my daughter use this for her science fair project? I bet she'd be the only third grader with a velocity stack comparison. (IMG:style_emoticons/default/biggrin.gif) Paul |
Jake Raby |
Nov 9 2004, 08:08 PM
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#7
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
That would be cool!!
The higher the engine is tuned, the more you will notice the changes from the stack variations. Thats why I'm gonna do this more..... The next 10 engines I have lined up is a very good mix of sizes and tuning from a 1911 clear to a 2563.... Did you change your jetting after you changed the stacks?? |
URY914 |
Nov 9 2004, 08:38 PM
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#8
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I built the lightest 914 in the history of mankind. Group: Members Posts: 121,115 Joined: 3-February 03 From: Jacksonville, FL Member No.: 222 Region Association: None |
QUOTE(Jake Raby @ Nov 9 2004, 06:08 PM) Did you change your jetting after you changed the stacks?? No I didn't but I'll look and see what I'm running now and what sizes I have. Paul BTW, I was kidding about the science fair thing. We're going to do a compairson between fiberglass, wood and carbonfiber. We're going to make F/G and C/F the same size as a wooden paint stiring stick. We'll put a weight on them and see which one bends the most. Simple.(IMG:style_emoticons/default/wink.gif) |
Jake Raby |
Nov 9 2004, 08:56 PM
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#9
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Check on the jets...
That sounds cool.... for the science fair.. Safer than mine, I made some home made napalm from the old styrofoam stuff and melted my desk the first time I showed the teacher.... She thought it was gonna be a volcano! |
Brett W |
Nov 9 2004, 11:23 PM
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#10
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Advanced Member Group: Members Posts: 2,856 Joined: 17-September 03 From: huntsville, al Member No.: 1,169 Region Association: None |
Thanks for showing that. Now people won't look at me wierd when I take the 6 inchers of their car and throw them across the yard.
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nebreitling |
Nov 9 2004, 11:28 PM
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#11
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Member Emeritus Group: Members Posts: 3,314 Joined: 26-March 03 From: San Francisco Member No.: 478 |
that's hilarious jake!
they took all the fun stuff out of chemistry sets about the time i was born... still managed to blow some beakers up. |
Jake Raby |
Nov 9 2004, 11:47 PM
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#12
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Brett, I had you in mind as well when I did the testing..
I'm gonna play with a bunch more combosand I just found my 4" stacks a few minutes ago while looking for my spray gun to paint the interior of the new shop! Damn place looks like the OR at the local hospital! Its so bright inside that I'll need shades to assemble things! The decks are super glossy epoxy and the walls are 3 coats of the same paint used on the underside of Delta aircraft.... every bench is stainless steel.. Its bitchin! BTW, I guess no one noticed those NOS foggers in the manifolds..... You should see what it did when I sprayed the juice to it! |
bperry |
Nov 10 2004, 12:09 AM
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#13
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Lurker Group: Members Posts: 477 Joined: 16-February 04 From: Dallas, Tx Member No.: 1,661 |
Just curious:
Is there interaction between the stack height/size and the intake manifold height/size? I ask because I seem to remember that either SCCA or PCA had some new rules for Carbs that require the use of the Pierce manifolds which are shorter than the CB ones. --- bill |
Jake Raby |
Nov 10 2004, 12:40 AM
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#14
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
absolutely... We are fighting with SCCA right now about the manifold situation... The Pierce manifold is still too tall for high revs and it is not the correct size under the butterfly for a 40mm carb, its like 48-50mm!
everything changes when the manidfold length changes, the CB manifold is a great street manifold, so I'm using it for the base for the testing.. I'll have 4 production engines to test this on very soon, as well as manifold length.. |
ChrisFoley |
Nov 10 2004, 05:29 AM
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#15
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I am Tangerine Racing Group: Members Posts: 7,937 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None |
I'm running 2" stacks on my race engines. I think I got them from PMO, same place I got my good manifolds.
I hope to have some more soon, to send down to you Jake. You didn't show the 1.7" stacks in your pics. Are they the cast plates that have no bell shape? |
Jake Raby |
Nov 10 2004, 09:59 AM
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#16
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
No, they are the stock dellorto stack....
Thanks for the work on the manifold stuff with SCCA Chris.. BTW, when are you sending down the rest of your goodies? |
Joe Bob |
Nov 10 2004, 10:41 AM
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#17
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Retired admin, banned a few times Group: Members Posts: 17,427 Joined: 24-December 02 From: Boulder CO Member No.: 5 Region Association: None |
Speaking of stacks.....does anyone have a line on some "interesting" stack cover/cleaners? Frankenstealth has the typical water shields...but since it is a rustypieceofshit and will never see the rain....it also does not have a top....I would like to dress up the intakes.... <_<
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spunone |
Nov 12 2004, 09:15 AM
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#18
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Senior Member Group: Members Posts: 945 Joined: 6-April 04 From: Anaheim CA Member No.: 1,901 Region Association: Southern California |
Hey Jake of the different stacks I make 90% are 3.5 inches tall don't know why but thought i'd pass it along (IMG:style_emoticons/default/smash.gif)
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HarveyH |
Nov 12 2004, 09:35 AM
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#19
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Member Group: Members Posts: 450 Joined: 19-June 03 From: Downingtown, PA Member No.: 843 |
(IMG:style_emoticons/default/ar15.gif) Hijack Alert (IMG:style_emoticons/default/ar15.gif)
URY914 said: QUOTE BTW, I was kidding about the science fair thing. We're going to do a compairson between fiberglass, wood and carbonfiber. We're going to make F/G and C/F the same size as a wooden paint stiring stick. We'll put a weight on them and see which one bends the most. I used to work at GE Aerospace, and I remember them making an antenna boom out of unidirectional graphite fiber - epoxy that was effectivly the dimensions of a 4" diameter pipe, 28 feet long. My understanding was that they hung 60,000 lbs off of the end of this thing (fully cantilevered) as a proof load (IMG:style_emoticons/default/wacko.gif) (IMG:style_emoticons/default/ar15.gif) End Hijack (IMG:style_emoticons/default/ar15.gif) Harvey |
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