I hear all this stuff. Kind of glad a went the cheap route. Rewiring a 6.0 harness was not near as hard as everyone thinks. My harness even looks good, and uses easy to find 6.0 litre plugs
CK5
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L18 8.1L swap resource thread
- Thread starter Larry
- Start date
At least they are not making mistakes with the pinning at the ECM.If it makes you feel any better, they used the wrong alternator plug and goofed up the EVAP leads on my latest harness for the L29 454 K5 I’m building now. I clearly told Troy that I was using a CS144 140-amp alternator, and they still used the oval plug that’s used on the base alternators. Then I told them I needed the EVAP Vent Valve circuit to be about 9 feet long as I had planned to mount the EVAP can somewhere towards the back of the rig. It showed up with a 9 feel long Purge Solenoid lead, which is on the intake, and nothing to go to the Vent Valve.. They were quick to sent me what I needed with the instructions where to pin the Vent Valve circuits in the ECM but geesh. It’s like, don’t you guys write this shit down?. I guess, I somewhat understand that these harnesses are kind of involved to build with large margins of error. I mean, that’s why I don’t build my own harnesses
and at the end of the day, Howell is probably still the best in the business.
One thing I did differently on this latest order was to order it bare and without looming, as it seems there are always circuits that are in the wrong spot, too short, too long, etc. They gladly did that and sent the looming and tape separately. I’m glad I did this because the MAF and IAT were on the wrong side.
I bought a brand new harness for my 12 liter CAT from the dealership and it didn't work.
We assumed it was some sensor or something else.
After 2 weeks of changing parts we started testing and the injectors were not getting power.
2 out of 70 pins were swapped.
so i need to swap a 8.1 i got in 1 of my trucks . its a short block now so figure toss in a cam . .
whats the best cam for towing / hauling not over 4k rpm with 4L80-e trans and 4.63 gears . . want the most swap in friendly no extra parts . i have a good local dyno jet tunner guy for the ecm part .
whats the best cam for towing / hauling not over 4k rpm with 4L80-e trans and 4.63 gears . . want the most swap in friendly no extra parts . i have a good local dyno jet tunner guy for the ecm part .
Did someone say cam?
This is the smallest cam I have ever recommended because you only want power to 4000 RPM, but here it is...
Tri-Power Xtreme 194/206 Hydraulic Roller Cam for GM 8100/8.1L
Tri-Power Xtreme 194/206 Hydraulic Roller Cam for GM 8100/8.1L
I could have it drop shipped to you.
You could step up to this one for a little more power, with a little more duration it would make more midrange.
Tri-Power Xtreme 202/212 Hydraulic Roller Cam for GM 8100/8.1L
Tri-Power Xtreme 202/212 Hydraulic Roller Cam for GM 8100/8.1L
Both have somewhat wide LSA at 115 - 116 and both have somewhat low lift that should work with factory heads and pistons. Though I would still check PtoV clearance anyway to be sure. Also, make sure your lifter preload is correct during assembly.
You should probably swap valve springs.
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DOH! You opened the door...here comes the flood.
Having felt what the Raylar stage 2 cam did in Larry’s burb I agree with Larry’s assessment that it ruined the low end torque production. It ran like a scalded dog north of 2500 rpm no doubt. But the bottom end was soggy below 2000 rpm. Like amazingly weak down low. I’m no cam wizard like Heath but I can say this if you like the 8.1’s low end grunt don’t get that cam. The stock Gm cam pulls so much better down low. It doesn’t wind out nearly as much as the Raylar cam did but spinning a 8.1 to 5,500+rpm to get power out of it is counter productive.
I won't use Raylar cams solely because they don't give you the specs. I won't use a cam I don't know the specs, and I don't like "stage blah blah" cams, especially without the specs. Sometimes the specs line up for a particular application and that's fine, but if you don't have the specs, who knows.
And I don't disagree, if you only want power below 4,000 RPM it's debatable whether the stock cam is the best. Because the more duration and overlap you go the more off idle torque you can lose.
This is why it was the smallest cam I have recommended. There is certainly room to gain in the 2500 - 4000 range, but you may lose off idle torque. If you have an automatic trans this likely doesn't matter. But if you have a manual and lug it at 1200 it would matter.
Also, if you get a cam that's good for 5,500 its pointless, you would lose torque below 2000 and the heads likely don't make power up there anyway.
It depends on what trans and what tire size @sweetk30 has. He has pretty low gearing at 4.63.
And I don't disagree, if you only want power below 4,000 RPM it's debatable whether the stock cam is the best. Because the more duration and overlap you go the more off idle torque you can lose.
This is why it was the smallest cam I have recommended. There is certainly room to gain in the 2500 - 4000 range, but you may lose off idle torque. If you have an automatic trans this likely doesn't matter. But if you have a manual and lug it at 1200 it would matter.
Also, if you get a cam that's good for 5,500 its pointless, you would lose torque below 2000 and the heads likely don't make power up there anyway.
It depends on what trans and what tire size @sweetk30 has. He has pretty low gearing at 4.63.
The other problem with the Raylar cam was the inconsistent idle. It had a lot of “chop” as the kids call it. Cool sounding but with mechanical throttle the iac struggled to keep up with the surge due to the choppy idle. So engine surged. Up and down at idle fluctuating a solid 2-300rpm. It made driving smooth at low speed with a manual challenging. Attempts were made with two separate tuners to correct the surge. When either couldn’t do it they fell back to recommending switching to a DBW electric throttle. That way they could control the surge by cracking the throttle blade slightly to control idle speed better. Larry wasn’t going to swap to a dbw setup so the raylar cam’s fate was sealed. It came out and a fresh stock Gm bump stick went in. And as they say they lived a happy ever after.
That sounds like it either had too tight of LSA for the application or something was wrong like a vacuum leak or something. Not knowing the specs, it's hard to diagnose. I certainly would not expect anything like that with the two cams I recommended. What RPM were you trying to idle at? With the cams I selected I would say it should idle pretty smooth at around 700 RPM, no fluctuations.
4L80-e / 4.63 gear / 225/70/19.5 drw setup dana 80 . 12ft flatbed and haul trailer and 4k lbs on bed . we have hills and flats around here . most elevation is 1,200-2,000 ft above sea level .
just figured if there was a good cam time is now . but if not worth it and or need tons of parts i will skip it . and even my stick shift truck pulling 10k trailer loaded all the time same combo but nv4500 i tend to hardly go past 3k but some times on big hill 3,500 max rpm .
They have half a dozen cams or so to work with stock heads/pistons and up to their heads.
With a torque converter and those gears/tires I would think you would see a performance gain. Below 1500 it may be lower but that shouldn't matter as the torque converter literally multiplies torque down low.
I think you may need new valve springs, but I am not sure, usually a don't use cams small enough to not need new valve springs, but this one it may be possible, I'm not sure. I could ask my comp guy if you need.
It says you don't need an adjustable valvetrain so it should be fine with the factory rockers and pushrods according to the catalog.
I guess you have to prioritize if you want more midrange or you would rather have more off idle torque. If you had the manual I think I would leave it stock for this application, but with your gears and the torque converter it could be beneficial. That's completely up to you.
It sounds like this truck is a tool for you, not a toy. So ask yourself this. Will the stock cam get the job done for what you want to do with it, or will you be wishing for more power.
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With my sub, 4l80 and 3.73, towing less than 3k, on 6%+ grade at 55 plus it will down shift to 2nd and run 4k rpm
@folki have read some guys like the zz502 gm cam and swap the firing order . But most i have seen are doing bigger rpm .
yes this is a work truck and just was thinking more bottom end grunt if possible within reason .
Its twin with the stick shift and 10ft bed . Just to give a idea of the way i work it . When full its 10k for trailer .
yes this is a work truck and just was thinking more bottom end grunt if possible within reason .
Its twin with the stick shift and 10ft bed . Just to give a idea of the way i work it . When full its 10k for trailer .
I wouldn't recommend the ZZ502 cam for your application, the LSA is way too tight, and the duration is too high for your application, you will lose quite a bit of bottom end and it will be more peaky. It will also idle a little lopey.
You want a nice flat torque curve.
I think it goes back to this...Will the stock cam get the job done for what you want to do with it, or will you be wishing for more power? If you want more, swap the cam.
I hear all this stuff, and it makes me glad I kept mine bone stock.
Easy to tune, parts available(within reason), and known good power in a very usable powerband
Easy to tune, parts available(within reason), and known good power in a very usable powerband
You'll never hear me say that...
i am with you on that... the little i drove my truck b4 the fire... I couldnt stop my bias ply tires from spinning without trying...albeit dbw needs setting cuz touch throttle to quarter and is like full throttle... once running again hptuners... I will be pickin yalls brains later on stock cam or higher... I trail ride and mud so rpms... but also need grunt for hill climns and pullin fullsizes out too
The beauty of the 8.1 is it’s really good in stock form for our heavy trucks. Despite the lack of options of high performance stuff for them even. Stock is simple, reliable as the day GM put it in a truck. Parts are available anywhere.
