AFR vs LT4 heads
Thread Starter
Drifting
Joined: Oct 2003
Posts: 1,405
Likes: 4
From: Lorena Texas
AFR vs LT4 heads
I am building an LT4 383 stroker and need advice on heads. I have a set of fresh LT4 proted heads but have heard that AFR's would be better. Car will be used mostly for track. Compression will be about 10.25 and cam has not been selected. Any advice would be appreciated.
Thanks
Thanks
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Depends on power goals and cam selection...and budget.
I went with the AFR 195 Eliminators with the competition porting. My cam is 230/236 @ .050 and lift is .62x / .62x I/E. I'm at 411rwhp using a Mustang Dyno which is 430-450 on a Dynojet dyno.
I use the car for track days. The power is great but I have to admit that I like the single mass flywheel the best. It makes heel/toe sooooo much easier since the engine revs
I went with the AFR 195 Eliminators with the competition porting. My cam is 230/236 @ .050 and lift is .62x / .62x I/E. I'm at 411rwhp using a Mustang Dyno which is 430-450 on a Dynojet dyno.
I use the car for track days. The power is great but I have to admit that I like the single mass flywheel the best. It makes heel/toe sooooo much easier since the engine revs
Thread Starter
Drifting
Joined: Oct 2003
Posts: 1,405
Likes: 4
From: Lorena Texas
Depends on power goals and cam selection...and budget.
I went with the AFR 195 Eliminators with the competition porting. My cam is 230/236 @ .050 and lift is .62x / .62x I/E. I'm at 411rwhp using a Mustang Dyno which is 430-450 on a Dynojet dyno.
I use the car for track days. The power is great but I have to admit that I like the single mass flywheel the best. It makes heel/toe sooooo much easier since the engine revs
I went with the AFR 195 Eliminators with the competition porting. My cam is 230/236 @ .050 and lift is .62x / .62x I/E. I'm at 411rwhp using a Mustang Dyno which is 430-450 on a Dynojet dyno.
I use the car for track days. The power is great but I have to admit that I like the single mass flywheel the best. It makes heel/toe sooooo much easier since the engine revs
Thanks
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Sent you a PM. For those that may be curious regarding my cam specs and CR...
Static compression ratio ended up just a little over 10.9:1. DCR, if I recall, is just a little over 8:1, so very pump gas friendly.
The cam is by CompCams and uses their CRC (Constant Radius of Curvature) lobes. As I recall, I have the 3194 lobe on the intake and the 3196 lobe on the exhaust. Here are the specs:
LSA is 113*, 2* advanced
Intake Centerline is 111
Advertised Duration: 282 / 286
Duration @ .050: 230 / 236
Duration @ .200: 157 / 157
Lift: .622 / .624
I spec'ed this cam to have a hp peak of ~6000rpm and I wanted street manners. On the dyno my hp peak was exactly 6000 rpms and it has great street manners
This cam idles way better than my old Hot Cam engine. I have the idle tuned to 825rpm and there is just a touch of lope. People are very surprised at the power and the street manners of this engine. Below 1200rpm in 4th or 5th gear there is a little cam surge but nothing major and frankly, how often do you drive at that rpm?
All the details and pictures of the build are in this thread: 383 Build...
Static compression ratio ended up just a little over 10.9:1. DCR, if I recall, is just a little over 8:1, so very pump gas friendly.
The cam is by CompCams and uses their CRC (Constant Radius of Curvature) lobes. As I recall, I have the 3194 lobe on the intake and the 3196 lobe on the exhaust. Here are the specs:
LSA is 113*, 2* advanced
Intake Centerline is 111
Advertised Duration: 282 / 286
Duration @ .050: 230 / 236
Duration @ .200: 157 / 157
Lift: .622 / .624
I spec'ed this cam to have a hp peak of ~6000rpm and I wanted street manners. On the dyno my hp peak was exactly 6000 rpms and it has great street manners
This cam idles way better than my old Hot Cam engine. I have the idle tuned to 825rpm and there is just a touch of lope. People are very surprised at the power and the street manners of this engine. Below 1200rpm in 4th or 5th gear there is a little cam surge but nothing major and frankly, how often do you drive at that rpm?
All the details and pictures of the build are in this thread: 383 Build...
Safety Car
Joined: May 2002
Posts: 4,659
Likes: 82
From: Toronto ontario
I believe if you go afrs you will need a new manifold. SO really you have to ask yourself what the upgrade might be worth. The AFrs no doubt flow better and will make more power. but you have to buy the heads, and an Lt1 manifold to gain what... and I'm not going to guess because I have no clue how well your ported lt4 heads flow.
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Team Owner
Joined: Mar 2001
Posts: 30,847
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From: Boston, Dallas, Detroit, SoCal, back to Boston MA
I believe if you go afrs you will need a new manifold. SO really you have to ask yourself what the upgrade might be worth. The AFrs no doubt flow better and will make more power. but you have to buy the heads, and an Lt1 manifold to gain what... and I'm not going to guess because I have no clue how well your ported lt4 heads flow.
Drifting
Joined: Aug 2000
Posts: 1,614
Likes: 0
From: Colleyville Texas
I am building an LT4 383 stroker and need advice on heads. I have a set of fresh LT4 proted heads but have heard that AFR's would be better. Car will be used mostly for track. Compression will be about 10.25 and cam has not been selected. Any advice would be appreciated.
Thanks
Thanks
Houston in 2001. 400RWTQ 3500-5000 RPM's. Horsepower peaked at 5800 RPM's and dropped below 400RWHP at 6000 RPM's. Had 28# LT4 injectors, stock LT1 intake, 52TB.
With the new AFR 195CC LT1 Eliminator competition heads, ported LT1 intake, 42# injectors, 58TB and the same Comp Cam XE 230/236 cam, the car is sitting at 440RWHP/434RWTQ with a mail order tune and very rich A/F. Should reach 450+ with a good dyno tune. 400RWTQ 3000-6000 RPM's. Horsepower peak at 6500 RPM's when we shut down the dyno.
CR is estimated at 11.8:1 now. Gas mileage is better with the new set up and car runs a little cooler.
Looked at having Lloyd Elliott clean up the old TPIS heads for $600 instead of buying the AFR heads. He felt the flow numbers would improve to 275-280 versus the 260 original TPIS numbers.
Melting Slicks
Joined: Jul 2004
Posts: 2,695
Likes: 0
From: Chicago Illinois
Those LT4 heads have a lot of meat on them. I experienced porter can make those things flow incredible #s. It might be cheaper then new AFR's. Ask these guys which heads flow better www.advancedinduction.com
Melting Slicks
Joined: Jul 2004
Posts: 2,695
Likes: 0
From: Chicago Illinois
clink this link and scroll down to the flow chart for ported LT4 heads http://www.advancedinduction.com/AiProductsLT4.html
