Lt4 conv., Speed Inc. dyno #'s
hehe 
08-05-2003, 12:11 PM
#32
Registered User
Join Date: Jun 2002
Location: Metro Detroit, MI
Posts: 1,373
Using dynojet's inflated numbers to calculate flywheel numbers is kinda pointless anyways. If you do a conversion based on the weight of my car and trap speed its capable of (let's say 115 mph w/ a 3350 lb car...). Using a trap/hp converter, it would say I have 420 hp. Take my mustang dyno number, divide by .82 and you'll get 426.x. Using a dynojet rwhp number, I would probably end up with 450+ hp at the flywheel, which might seem great but just isn't true.
08-05-2003, 12:19 PM
#33
Registered User
Join Date: Aug 2002
Location: JoCo KS
Posts: 305
Originally posted by ltlhomer
Using dynojet's inflated numbers to calculate flywheel numbers is kinda pointless anyways. If you do a conversion based on the weight of my car and trap speed its capable of (let's say 115 mph w/ a 3350 lb car...). Using a trap/hp converter, it would say I have 420 hp. Take my mustang dyno number, divide by .82 and you'll get 426.x. Using a dynojet rwhp number, I would probably end up with 450+ hp at the flywheel, which might seem great but just isn't true.
Using dynojet's inflated numbers to calculate flywheel numbers is kinda pointless anyways. If you do a conversion based on the weight of my car and trap speed its capable of (let's say 115 mph w/ a 3350 lb car...). Using a trap/hp converter, it would say I have 420 hp. Take my mustang dyno number, divide by .82 and you'll get 426.x. Using a dynojet rwhp number, I would probably end up with 450+ hp at the flywheel, which might seem great but just isn't true.
EDIT: I would think the trap/hp calculators would be even more unreliable because the trap speed includes things such as driver ability, traction, etc. Why would those matter to FWHP numbers? In the end the only real way is to connect the engine directly up to an engine dyno and run the tests. In the interim I'd trust the dyno to be more accurate than trap times.
Last edited by BitCypher; 08-05-2003 at 01:08 PM.
08-05-2003, 05:45 PM
#36
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Thread Starter
Join Date: Aug 2002
Location: Winthrop Harbor Il.
Posts: 31
Originally posted by BitCypher
No problem bud, it's real easy to do it the wrong way. Let's see if I can explain it...
Let's say that a V8 motor strapped to an engine dyno pulled 300hp (fwhp). Now let's say that that engine was bolted into a car with an automatic transmission and strapped to a vehicle dyno. What's the estimated RWHP?
Condering that most A4 setups eat approximately 18% of the engine's output (to turn the tranny, drive-shaft, and rear-end) then the approximate RWHP in this case could be calculated by simply asking "What is 82% of 300?":
300 * .82 = ??? [answer = 255]
Cool, 255rwhp for that setup. Okay, but what if you only had the RWHP number (percentage of an unknown 'whole') and wanted to find FWHP (the unknown 'whole')? The approximate FWHP can be found by reversing the above formula (divide each side of the equation by .82) to ask "255 is 82% of what number?":
??? = 255 / .82 [answer = 300]
Note that the INCORRECT question would've been "255 is 118% of what number?". That would give a lower number because 18% of 255 is not equal to 18% of 300; or ".18 * 255 < .18 * 300". Make sense?
So, in summary:
whole * percentage = percentage_of_whole
percentage_of_whole / percentage = whole
Just remember that the engine is the source of all this power, so the engine's FWHP is always the "whole".
Hope this helps!
No problem bud, it's real easy to do it the wrong way. Let's see if I can explain it...
Let's say that a V8 motor strapped to an engine dyno pulled 300hp (fwhp). Now let's say that that engine was bolted into a car with an automatic transmission and strapped to a vehicle dyno. What's the estimated RWHP?
Condering that most A4 setups eat approximately 18% of the engine's output (to turn the tranny, drive-shaft, and rear-end) then the approximate RWHP in this case could be calculated by simply asking "What is 82% of 300?":
300 * .82 = ??? [answer = 255]
Cool, 255rwhp for that setup. Okay, but what if you only had the RWHP number (percentage of an unknown 'whole') and wanted to find FWHP (the unknown 'whole')? The approximate FWHP can be found by reversing the above formula (divide each side of the equation by .82) to ask "255 is 82% of what number?":
??? = 255 / .82 [answer = 300]
Note that the INCORRECT question would've been "255 is 118% of what number?". That would give a lower number because 18% of 255 is not equal to 18% of 300; or ".18 * 255 < .18 * 300". Make sense?
So, in summary:
whole * percentage = percentage_of_whole
percentage_of_whole / percentage = whole
Just remember that the engine is the source of all this power, so the engine's FWHP is always the "whole".
Hope this helps!
08-23-2003, 10:15 PM
#38
Registered User
Join Date: Nov 2001
Location: Summerfield, NC USA
Posts: 719
Originally posted by Chris 96 WS6
I will say those are probably typical or average power numbers for the LT4 conversion, but you could have gotten quite a bit more power by doing a little more research and for the same and maybe a tad less $$.
My mods:
Stock heads ported by Lloyd with 2.00/1.56 valves
XE 224/230 cam, 114LSA, 110ICL
1.6 non-self aligning rockers, guideplates, hardened pushrods
Cmotorsports "618" valvesprings
LT4 extreme duty timing chain
FLP longtubes, cutout
BBK 58mm TB
I will say those are probably typical or average power numbers for the LT4 conversion, but you could have gotten quite a bit more power by doing a little more research and for the same and maybe a tad less $$.
My mods:
Stock heads ported by Lloyd with 2.00/1.56 valves
XE 224/230 cam, 114LSA, 110ICL
1.6 non-self aligning rockers, guideplates, hardened pushrods
Cmotorsports "618" valvesprings
LT4 extreme duty timing chain
FLP longtubes, cutout
BBK 58mm TB
Porting, valves, springs, retainters, cam, etc etc, if you have a breakdown and total it would benefit me a little better.
Thanks,
08-24-2003, 08:35 AM
#39
Registered User
Join Date: Jun 2002
Location: Metro Detroit, MI
Posts: 1,373
xe230/236 (.544 / .555 w/ 1.6's) $210
Comp. pro mag 1.6's nsa w/ guideplates $270
Stock hardened pushrods
Stock TB
30# svo's (not actually needed...just bought for extra safety. fwiw, dyno runs were done w/ 22 #'s) $250
Used cnc ported stock casting heads $800
Unported stock intake
Spring setup $120 installed
Jet hot hooker lt's $620
Vigi 3000 stall $475 used
True dual setup (parts=180 installation=175)
347.9 rwhp on MD which equates to 380-400 on a dynojet and that's through an auto and a vigi stall.
It has spanked many 02+ 911 tt's, ferrari 360 modenas, non 03 vipers, and of course many other not-as-exciting cars. I probably wouldn't fair so well if we were racing up to 150+ but it's not like you can do that on your typical str...track.
Hope that helps you out...if you have any other questions feel free to email me at LTLHOMER@aol.com. I'm up at college and it can get quite boring. I still want to line up and race this kid with a 409 stroker setup for juice in a 2002 anniv. ss. I know I'll get murdered (n/a pretty bad and w/ n2o super bad) but it's always fun to see fast *** cars getting up on it.
Comp. pro mag 1.6's nsa w/ guideplates $270
Stock hardened pushrods
Stock TB
30# svo's (not actually needed...just bought for extra safety. fwiw, dyno runs were done w/ 22 #'s) $250
Used cnc ported stock casting heads $800
Unported stock intake
Spring setup $120 installed
Jet hot hooker lt's $620
Vigi 3000 stall $475 used
True dual setup (parts=180 installation=175)
347.9 rwhp on MD which equates to 380-400 on a dynojet and that's through an auto and a vigi stall.
It has spanked many 02+ 911 tt's, ferrari 360 modenas, non 03 vipers, and of course many other not-as-exciting cars. I probably wouldn't fair so well if we were racing up to 150+ but it's not like you can do that on your typical str...track.
Hope that helps you out...if you have any other questions feel free to email me at LTLHOMER@aol.com. I'm up at college and it can get quite boring. I still want to line up and race this kid with a 409 stroker setup for juice in a 2002 anniv. ss. I know I'll get murdered (n/a pretty bad and w/ n2o super bad) but it's always fun to see fast *** cars getting up on it.
08-24-2003, 10:20 AM
#40
Registered User
Join Date: Aug 2003
Location: jacksonville, FL
Posts: 515
Wow, some really nice and informative posts, guys. I was thinking about doing a full LT4 conversion, but after reading all these posts, I might be better off doing something else. Perhaps you guys can help. I'm looking for between 350-400rwhp, and I have about $3500 to spend. Please take a look at my signature info and see what I already have done and tell me if you guys think I should just get the full LT4 conversion kit or if I should spend teh majority of my $$$ on AFR heads and a nice comp cam. I need some expert help in this field as they are high $$ mods and I want to do it right from the start! Keep in mind, I'm doing the OBD I conversion soon with custom tuning. Thanks everybody.
08-29-2003, 08:59 AM
#41
Registered User
Join Date: Nov 2001
Location: Summerfield, NC USA
Posts: 719
Thanks for all the info guys.
My luck w/ used equipment is pretty bad, let alone w/ new stuff. I went ahead and dropped a bomb on the LT4 conversion from summit. I live 20 minutes from gm parts direct, and they won't let you counter pickup, and no phone number to contact for support, so i gladly sent my $ to summit. Should be on my door step today, can't wait. I'm also doing the vented opti conversion while I'm at it, getting rid of all the little things while the wife is still in shock.
Got 30# SVO injectors, my old injectors got clogged to the hilt w/ rust from the stock S-10 fuel line sitting out in the open for a couple of months. Got new aluminum line to run to the motor, BBK 52mm TB, and taylor over the valve cover wire conversion.
Hopefully will have it back on the road in 2-3 weeks pending I don't find anything major when I finally get the pass. side head off.
My luck w/ used equipment is pretty bad, let alone w/ new stuff. I went ahead and dropped a bomb on the LT4 conversion from summit. I live 20 minutes from gm parts direct, and they won't let you counter pickup, and no phone number to contact for support, so i gladly sent my $ to summit. Should be on my door step today, can't wait. I'm also doing the vented opti conversion while I'm at it, getting rid of all the little things while the wife is still in shock.
Got 30# SVO injectors, my old injectors got clogged to the hilt w/ rust from the stock S-10 fuel line sitting out in the open for a couple of months. Got new aluminum line to run to the motor, BBK 52mm TB, and taylor over the valve cover wire conversion.
Hopefully will have it back on the road in 2-3 weeks pending I don't find anything major when I finally get the pass. side head off.
08-29-2003, 03:07 PM
#43
Registered User
Join Date: Dec 2000
Location: Alta Loma, CA
Posts: 1,320
Originally posted by 30thannZ28
...looking for between 350-400rwhp, and I have about $3500 to spend. Please take a look at my signature info and see what I already have done and tell me if you guys think I should just get the full LT4 conversion kit or if I should spend teh majority of my $$$ on AFR heads and a nice comp cam.
...looking for between 350-400rwhp, and I have about $3500 to spend. Please take a look at my signature info and see what I already have done and tell me if you guys think I should just get the full LT4 conversion kit or if I should spend teh majority of my $$$ on AFR heads and a nice comp cam.
If you do get AFR heads, DO NOT HAVE AFR PORT THEM! Send them out to someone reputable from this list. Also, if you're going to go with AFR heads, why not pick up an LT4 intake for cheap, and then you can order a set of AFR LT4 heads, which will give you a little more potential. This is what I plan on doing.
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