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Thread: "New" guy

  1. #1
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    "New" guy

    Good evening gentlemen, registered here a while ago, mostly to see pics of others builds and what not. Lurked ... old (current) engine is a stock 95 TBI with Vortec heads, beehive springs, stock 350 TBI with "free mods" and the stock flat tappet TBI cam. I find myself currently at the tail end of building a new engine. 6 inch rod 355, 2vr flat top pistons, Vortec heads with LS6 beehive springs again. Currently have an LT4 Hot Cam and Holley 670 TBI in my possession, was told by a tuner there is no way this will work in my application, 3.90 gear 4door 2WD Tahoe. Too heavy, will need too many RPMs, etc. I'm fine with another cam, the Lunati 20080660 was the one suggested. The Hot Cam was for another project that never happened. I didn't want to get another TBI unit or cam if someone can help me make this work and it will make power where I need it. I'm going to be doing a lot of reading over the next few weeks. I have TunerPro (think that was the name of the software) on my old notebook, did some data logging and looking with an ALDL cable, never burned a chip but I see that's far cheaper and easier now. Any thoughts? Am I crazy? Am I screwed? Do I need new parts? What's that smell?

  2. #2
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    Quote Originally Posted by retorq View Post
    Good evening gentlemen, registered here a while ago, mostly to see pics of others builds and what not. Lurked ... old (current) engine is a stock 95 TBI with Vortec heads, beehive springs, stock 350 TBI with "free mods" and the stock flat tappet TBI cam. I find myself currently at the tail end of building a new engine. 6 inch rod 355, 2vr flat top pistons, Vortec heads with LS6 beehive springs again. Currently have an LT4 Hot Cam and Holley 670 TBI in my possession, was told by a tuner there is no way this will work in my application, 3.90 gear 4door 2WD Tahoe. Too heavy, will need too many RPMs, etc. I'm fine with another cam, the Lunati 20080660 was the one suggested. The Hot Cam was for another project that never happened. I didn't want to get another TBI unit or cam if someone can help me make this work and it will make power where I need it. I'm going to be doing a lot of reading over the next few weeks. I have TunerPro (think that was the name of the software) on my old notebook, did some data logging and looking with an ALDL cable, never burned a chip but I see that's far cheaper and easier now. Any thoughts? Am I crazy? Am I screwed? Do I need new parts? What's that smell?
    I have a Lunati version of the Hotcam in my Express van with 1.6 rockers. It pulls the van around with ease and pulls strong to 5,800 with the GM L31 Marine intake. Stock B82 GM 4L80E torque converter stalls about 2,300 rpm and I have 4.56 gears and 29" tall tires. It pulls my 6,000 lbs Jayco travel trailer down the highway at 65-70 mph in overdrive at about 2,600-2,800 rpm with no issues. About to swap the intake for an Edelbrock proflow with a 90mm forward facing LS throttle body and put my Etec 170s back on after I had them surfaced(warped them when I overheated it a while back). I put down 290 rwhp @ 5,800 and 330 rwtq @ 4,000 with more than 300 rwtq @ 2,500 on a Mustang dyno that is super stingy. The Lunati Hotam with 4.56s pulls better in OD than the Marine cam did with 3.73s in 3rd. The tiny 196/206 marine cam only put down 230 @ 4,400 rwhp and 304 rwtq@ 3,400. When I hit a hill the thing only downshifts to 3rd vs 2nd before and I run up the same hill turning about 800 rpm less at the same speed. In the 3,500+ range the Hotcam has ALOT more TQ than the Marine cam.
    Last edited by Fast355; 4 Weeks Ago at 06:19 PM.

  3. #3
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    Quote Originally Posted by Fast355 View Post
    I have a Lunati version of the Hotcam in my Express van with 1.6 rockers. It pulls the van around with ease and pulls strong to 5,800 with the GM L31 Marine intake. Stock B82 GM 4L80E torque converter stalls about 2,300 rpm and I have 4.56 gears and 29" tall tires. It pulls my 6,000 lbs Jayco travel trailer down the highway at 65-70 mph in overdrive at about 2,600-2,800 rpm with no issues. About to swap the intake for an Edelbrock proflow with a 90mm forward facing LS throttle body and put my Etec 170s back on after I had them surfaced(warped them when I overheated it a while back). I put down 290 rwhp @ 5,800 and 330 rwtq @ 4,000 with more than 300 rwtq @ 2,500 on a Mustang dyno that is super stingy. The Lunati Hotam with 4.56s pulls better in OD than the Marine cam did with 3.73s in 3rd. The tiny 196/206 marine cam only put down 230 @ 4,400 rwhp and 304 rwtq@ 3,400. When I hit a hill the thing only downshifts to 3rd vs 2nd before and I run up the same hill turning about 800 rpm less at the same speed. In the 3,500+ range the Hotcam has ALOT more TQ than the Marine cam.
    That is certainly promising information!

  4. #4
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    Quote Originally Posted by retorq View Post
    That is certainly promising information!

    My buddy ran one in a Vortec head 350 tbi in a 1995 C1500 that was lifted on 32" tall tires. Had a 4L80E that came from a 6.5 diesel. Even with the stock 1,000 rpm diesel stall speed and 3.73s it ran well. Had an edelbrock victor jr 2bbl intake on it as well. It lagged a little on a WOT hit from a stop but it would run 0-60 in 1st gear. Once it got a little rpm built up it pulled HARD. He ran the MAF TBI 4L60E ECU code that Adam over on Thirdgen.org wrote.
    Last edited by Fast355; 4 Weeks Ago at 12:34 PM.

  5. #5
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    I've done a lot of builds similar to yours but with carbs on them. I cant see why it wouldn't work great in a Tahoe with a Holley TBI on it. I think it would like a slightly higher stall. ( like the S-10 converter) I've never tuned a Holley TBI so keep us informed. I have one coming up soon.

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    When presented with high lift / shorter duration or low lift / longer duration for EFI, a good general rule is to pick lift if possible. The cam recommended by the tuner may not be all that different from the HOT cam. It's got less lift and slightly more duration. The difference in ICL (1 degree) could disappear in manufacturing. The HOT cam has fairly mild ramps and I'm betting the Lunati version is the same. I'd have no problem running the HOT cam.

    And I think your tuner would choke if told I'm using a 302 with a smaller cam in a Suburban. My truck has 3.42's and it tows a trailer. I originally built the engine with an LT4 stock cam for an S10 Blazer but changed to the Marine cam before the engine was installed. Short stroke engines tend to like smaller cams.

    The HOT cam has little overlap and makes strong and steady vacuum. In a heavy truck with an automatic it will prefer a looser converter. If you're in an area with lots of hills you might tune for faster unlock of TCC on the highway and let the converter work for you. You might also tune for 4 -> 3 downshifts at lower throttle angle.

    Put the biggest dang cooler you can on that transmission. The trans will be expected to shift and in some cases a looser converter generates more heat.

    Do your prep work on that Holley TBI. I don't know how old it is but you need to be sure you have it in good shape before tuning begins. Understand what injectors are installed, make sure the throttles close properly, and make sure the IAC works.

  7. #7
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    Quote Originally Posted by 1project2many View Post
    When presented with high lift / shorter duration or low lift / longer duration for EFI, a good general rule is to pick lift if possible. The cam recommended by the tuner may not be all that different from the HOT cam. It's got less lift and slightly more duration. The difference in ICL (1 degree) could disappear in manufacturing. The HOT cam has fairly mild ramps and I'm betting the Lunati version is the same. I'd have no problem running the HOT cam.And I think your tuner would choke if told I'm using a 302 with a smaller cam in a Suburban. My truck has 3.42's and it towns a trailer. I originally built the engine with an LT4 stock cam for an S10 Blazer but changed to the Marine cam before the engine was installed. Short stroke engines tend to like smaller cams. The HOT cam has little overlap and makes strong and steady vacuum. In a heavy truck with an automatic it will prefer a looser converter. If you're in an area with lots of hills you might tune for faster unlock of TCC on the highway and let the converter work for you. You might also tune for 4 -> 3 downshifts at lower throttle angle. Put the biggest dang cooler you can on that transmission. The trans will be expected to shift and in some cases a looser converter generates more heat.Do your prep work on that Holley TBI. I don't know how old it is but you need to be sure you have it in good shape before tuning begins. Understand what injectors are installed, make sure the throttles close properly, and make sure the IAC works.
    I assume you mean pick higher lift, less duration, right?There are only small differences in the cams, I will be running 1.6 stainless full roller rockers on this setup. The lift/duration of the Lunati are quoted at 1.5, the Hot Cam numbers are quoted with 1.6 already I believe. There is some math to see exactly how close they are. I've seen others running the LT4 Hot Cam with Vortec heads in 350s, even wit TBI induction so my philosophy is, if they can do it so can I! Just the time it takes to get it there is the issue. My tuner would choke if he knew I was here lol!I'm one step ahead on the trans cooler. I have new lines and a big x large B+M plate style cooler ready to go in, just waiting to pull the engine to have full access to everything in there. The trans was rebuild a few years ago, 5 pinion GM planetaries, GM turbolator steels, upgraded band with matching clutches, Superior shift correction kit, Transgo plate, turlon balls, Sonnax .500 boost valve, Sonnax input drum reinforcement kit, Sonnax "Smart" shell, 36 element sprag, new electronics, deep cast AL pan with the correct filter. I do have a higher stall converter but it's been a few years since that was ordered, I am not sure what exactly it is. I do know with the current engine config I can hold it to about 2000/2100rpms and not much more. Worst case scenario, since I don't have to get a new cam and TBI unit, I can throw a few bucks at a name brand verified high stall convertor if needed. :DThanks for your thoughts, they have certainly helped.

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    Yes, as a general rule, when faced with two cams that offer similar performance for EFI, opt for more lift instead of greater duration.

    Increasing rocker ratio increases duration at .050" as the lift is achieved sooner in cam rotation and does not come again for a greater number of degrees. So GM cam would show less at 1.5 while Lunati would show more at 1.6.

    Sounds like the trans has been in good hands. Lotsa $$ in those parts but sometimes that's the only way to keep a '60E together.

    My tuner would choke if he knew I was here lol!
    Well, not everything we suggest here agrees with what pro tuners and magazines say. And in all fairness a conservative tuner would suggest a path that is most likely to promise success for both the customer and the tuner. As always, YMMV.

  9. #9
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    The Lunati cam has slightly less advertised duration, the same duration at .050, but more lift and slightly faster ramp rates. It also has 1 more advance built in. The GM Hotcam drops in on a 109 ICL and the Lunati a 108. The difference in performance would be pretty negligable between the two. The Lunati has .536/.536" lift with 1.6s. I bought the Lunati cam dirt cheap when Lunati was clearancing them a couple of years ago. They were ssomething like $80.00 shipped.

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    The Lunati has .536/.536" lift with 1.6s.
    Interesting. But are we talking about the same cams? The Lunati numbers currently published for the 20080660 mentioned above show a dual pattern cam with 279/287 advertised duration and .477"/ .502" lift with 1.6 rockers.

    http://www.lunatipower.com/ProductGr...?id=261&cid=59
    https://www.summitracing.com/parts/lun-20080660

    Lunati's 20120120 looks like it is a good match for the GM HOT cam:
    http://www.lunatipower.com/Product.aspx?id=3161&gid=337

  11. #11
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    Quote Originally Posted by 1project2many View Post
    Interesting. But are we talking about the same cams? The Lunati numbers currently published for the 20080660 mentioned above show a dual pattern cam with 279/287 advertised duration and .477"/ .502" lift with 1.6 rockers.

    http://www.lunatipower.com/ProductGr...?id=261&cid=59
    https://www.summitracing.com/parts/lun-20080660

    Lunati's 20120120 looks like it is a good match for the GM HOT cam:
    http://www.lunatipower.com/Product.aspx?id=3161&gid=337

    The 2nd cam you listed looks like the same grind, but for a retrofit roller application. Mine is for a stock roller cam setup. Lunati has updated the part number to 20080130 from 10030.

    http://www.lunatipower.com/CamSpecCa...rtNumber=10030

    GM Hotcam is 279/287* advertised at lash point.
    Last edited by Fast355; 3 Weeks Ago at 11:44 AM.

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