Btr truck cam with a manual?
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Teching In
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Btr truck cam with a manual? Hello, i was wondering if it would be ideal to run a btr stage 3 cam on my 5.3 with a gto t56 behind it. The motor/trans is in a 1988 Rx-7, Will the cam will affect the drivability with a t56?
Sounds like a cool project.
Can you tell us more about the car like its other mods and planned mods? Likewise how do you plan to use the car? What sort of goals do you have for the car?
That sort of info is always helpful
Can you tell us more about the car like its other mods and planned mods? Likewise how do you plan to use the car? What sort of goals do you have for the car?
That sort of info is always helpful
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Joined: Jun 2016
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From: Central Cal.
What do you see as the downside of using the BTR Stage 3 truck cam in his application? Not doubting you, just curious...
With the truck cam it should have way more than enough low end, be snappy and fun, but if you want it to go faster (especially ET wise) I'd go for a little different cam.
I'm in no way saying the truck cam won't work. It absolutely will.
Edit: forgot he said he is going with a T56. The same principals still apply but since I went off about 4L60's and stalls I figure I should at least note that I acknowledge he is running a T56 lol
Double edit: the only reason I said anything at all is because he asked if it would be "ideal". No the truck cam isn't ideal, but it's far from bad.
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From: Central Cal.
If it's a 5.3 with 706/862 heads, they don't flow enough to support .600 lift. .550 is about the max, if that. 243's, yeah. Larger valves, ports a bit bigger.
If you can, catch a video called "How to Properly Select a Camshaft" by Myvintageiron7512. It goes into how not to get too big a cam for the heads being used, and a lot more.
If you can, catch a video called "How to Properly Select a Camshaft" by Myvintageiron7512. It goes into how not to get too big a cam for the heads being used, and a lot more.
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If it flows best at 550, you want more than 550 lift so that it spends more time up in that area, if they max out at 550 and you only give it 545 to 550 then it just touches max flow then goes away. If it flows best at 550 and you give it 570 it goes past 550 twice....
That's the cliff notes. There's plenty more about it out there
And also, Texas speed has posted a bunch graphs and overlays comparing their truck cams in stock 5.3 truck motors with 550 lift cams and 600 lift cams and the 600 lift cams make more power everywhere than the 550 cam does, with ALL other specs being the same. Pretty sure that was ran on a 706 headed motor IIRC
That's the cliff notes. There's plenty more about it out there
And also, Texas speed has posted a bunch graphs and overlays comparing their truck cams in stock 5.3 truck motors with 550 lift cams and 600 lift cams and the 600 lift cams make more power everywhere than the 550 cam does, with ALL other specs being the same. Pretty sure that was ran on a 706 headed motor IIRC
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Verdad Gallardo TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
The problem with too much lift is reversion when flow stalls.
Unless I'm mistaken, TSP's tests were on a Gen IV 5.3 with 243/799 heads which do flow more than 706 heads. I'll check and edit if needed.
Unless I'm mistaken, TSP's tests were on a Gen IV 5.3 with 243/799 heads which do flow more than 706 heads. I'll check and edit if needed.
If it's a 5.3 with 706/862 heads, they don't flow enough to support .600 lift. .550 is about the max, if that. 243's, yeah. Larger valves, ports a bit bigger.
If you can, catch a video called "How to Properly Select a Camshaft" by Myvintageiron7512. It goes into how not to get too big a cam for the heads being used, and a lot more.
If you can, catch a video called "How to Properly Select a Camshaft" by Myvintageiron7512. It goes into how not to get too big a cam for the heads being used, and a lot more.
To add to this, port stalling found on a flowbench is going to move upward in lift once intake manifold is bolted on, due to the intake slowing the air down from restrictions not found on a flowbench.
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From: Central Cal.
Che70velle, you make a lot of sense. I based my theories (NOT facts... ) on what I'd heard, plus the video referenced in Post #7 above.
I have a feeling somethings you mention were not considered in the video.
I have a feeling somethings you mention were not considered in the video.
Lower lift isn't really about reversion. Reversion is more about large duration and LSA selected. I used to have SBC with a 240/250 @.050 on a 110 with barely .510 lift that had massive reversion.
If concern with the stalling for a certain lift one would want to test the heads on the flow bench and test the heads with the intake manifold in place. The manifold runner can affect the stall point. Sometimes making it lower and sometimes raising it to allow the heads to hold on longer.
The intake port can back up on the flow bench with more lift but that's mostly because the heads aren't set up correctly to support the cam. My understanding is often there is an issue with the short side radius and or valve job etc. To some degree those nasty flow bench events aren't quiet so bad in a running engine most of the time and that sort thing isn't much of issue. Ie head stalled at .570 lift and you have a .580 or so lift cam.
BTW - If the intake port in a LS head is stalling after ~ merely .550 lift - you can be sure the port work and or valve job in that cylinder head are suboptimal. Two outstanding head porters ( Darrin Morgan was one of them) told me that if the port work stalls under 1 inch lift its not a correctly optimized port/ valve job.
Last edited by 99 Black Bird T/A; Aug 8, 2020 at 01:26 AM.