[Nabush]

Originally Posted by oldman

I actually looked at a LT4 retrofit, they look great, have a OEM stock appeal and build quality and can be found heck of cheap. Also the LT5 cam is basically the LT1 manual cam (not made as GM just made all engines DoD). For altitude this is going to give you the bang for the buck period. I do the smallest CM blower cam with a custom .596 lift, if you don't want to go back to DoD or you don't want to by the LT5 cam. The CM will give you the big fuel lobe (you want that).
https://cammotion.com/gen5-lt-camsha...220-236-118-4/

Tell me where you find an LT4 cheap ? The cheaper I've seen is at $12,000 and I don't trust the seller....

Don't forget I need the dry sump version as it's a C7 GrandSport...

[Nabush]

Originally Posted by Dads1le

Here’s my pray performance ported heads and ported msd package with a ported stock 89 tb. 17/8 arh headers. Cam is 223/231. 111+3. Has very good low and midrange. Have since this dyno installed a ported 95 and picked up 5-10 midrange hp /tq with no top end increase

These are the 2 power curves that Bryan from GPI sent me for similar configs as mine, with their stage 3. 2nd has milled heads

[oldman]

the curves are not similar, hard to believe these are similar engine builds. Did you check the torque tables et al? I'm not that great at tuning, but would agree air flow never lies.

I keep forgetting you have a Vette. Maybe it would be cheaper to build from scratch? You can do drop in rods / pistons, valves and a smaller cam. Pick the blower of your choice, the Camaro LT4 conversions are inexpensive. But HP is addicting and your engine may rapidly run out of head room with the LT4 setup.

[cmitchell17]

I figured I would post up a airmass comparison I just did with some old data logs I had. I compared some airmass readings I had before I put my TSP stage 1/2 cam and TSP PRC ported heads on. I also globally multiplied each run by the corresponding "Air Density Engine Torque Multiplier". I understand this really isn't' what you're supposed to do given I am graphing air mass, but I did it more so since we are comparing one to one and trying to see power output as a result of increased/decreased airmass.



I am extremely unimpressed by my TSP cam/ported heads on my LT1. Yes I know there are a lot of other factors and I also have completely stock NPP exhaust and a ported stock intake manifold and throttle body, but my airmass is basically the same as it was before the cam at it moved way high up in the rpm range relative to my decently small cam (228/236, .635/.635, 114 LSA).

Also oldman, do you have the dynosim software? I am really thinking about getting it, but as a engineer I feel guilty that I am not trying to develop the equations and calculate things myself haha

[6spdhyperblue]

If you look at the OPs tune you can see there’s opportunity there

[Redlinez]

cmitchell17, the stock NPP flows quite well. The ported stock IM/TB isn't killing you either, a ported MSD would just help up top and you might lose even more down low than you might have with the heads/cam. They typically shift your power up higher. Do you have before and after dyno runs?

[cmitchell17]

Originally Posted by Redlinez

cmitchell17, the stock NPP flows quite well. The ported stock IM/TB isn't killing you either, a ported MSD would just help up top and you might lose even more down low than you might have with the heads/cam. They typically shift your power up higher. Do you have before and after dyno runs?

No I don't have any dyno runs at all, and when I say stock exhaust I mean stock cats and headers too.

[KingLT1]

The stock exhaust from the cats forward is indeed limiting his setup. Mainly the factory cats. The factory NPP cat back is not.


The stock IM/TB even ported limits the potential of a stage 2-3 head cam combo. The only way I would stick with a Stock ported IM/TB is on a mild stage 1 H/C setup where shift points would be similar to stock(64-6500rpm). Other then that you need a intake that carries the power up top better and utilizes the cams potential. Good news is the LT2 looks like a cheap upgrade that will definitely carry power much better up top.


The biggest mistake I have seen over the years and it applies to all GM small blocks is folks putting too large of a cam in the engine, not properly addressing the induction, exhaust, and not revving it high enough. Seen this for years on LS combos. Another big mistake I see with those doing heads/cam setups is leaving the stock compression. That is why you lose low end and mid range because you lost a lot of DCR from the bigger cams lack of efficiency down low...especially after you delete VVT. You need to raise the compression to get that back.

[cmitchell17]

Originally Posted by KingLT1

The stock exhaust from the cats forward is indeed limiting his setup. Mainly the factory cats. The factory NPP cat back is not.


The stock IM/TB even ported limits the potential of a stage 2-3 head cam combo. The only way I would stick with a Stock ported IM/TB is on a mild stage 1 H/C setup where shift points would be similar to stock(64-6500rpm). Other then that you need a intake that carries the power up top better and utilizes the cams potential. Good news is the LT2 looks like a cheap upgrade that will definitely carry power much better up top.


The biggest mistake I have seen over the years and it applies to all GM small blocks is folks putting too large of a cam in the engine, not properly addressing the induction, exhaust, and not revving it high enough. Seen this for years on LS combos. Another big mistake I see with those doing heads/cam setups is leaving the stock compression. That is why you lose low end and mid range because you lost a lot of DCR from the bigger cams lack of efficiency down low...especially after you delete VVT. You need to raise the compression to get that back.

But do we have options for raising compression besides the usual mill .030 from the heads? Without getting into serious money and complete engine builds with pistons of course.

[Redlinez]

"Another big mistake I see with those doing heads/cam setups is leaving the stock compression. That is why you lose low end and mid range because you lost a lot of DCR from the bigger cams lack of efficiency down low...especially after you delete VVT. You need to raise the compression to get that back.". That is excellent information and advice that only guys who truly understand engine theory can explain and good shops should know. I remember Pray talking about this too. Didn't realize he had stock manifolds and cats, definitely not helping. Cam choice is super important and too many people bite off on big lift and duration. Futral got me on my LS1 back in the day.

[Nabush]

On my end I don't have stock cats and stuff...


- Ported MSD
- Ported 95mm by Solers Performance
- ARH 1-7/8 Headers and X pipe

Even without raising compression the cam package should work fine, you see a lot of examples of totally decent numbers with stock compression.


I decided to buy a full Katech Stage 2 engine and sell mine in parts. I know the engine Katech sells me makes 600HP/530 FtLbs on pump gas. It has a smaller camshaft ("Torquer LT1 cam") but it keeps VVT so it makes torque everywhere, which is the best for my application (Roadcourse and AutoX). I also believe more their experience as far as valvetrain than TSP, as they do extensive durability and studies with their spintron valve test cell. They also have real racing experience.

I'm tired of spending so much time figuring out the issue...Having a peaky engine is fun in a way but not efficient enough for my use.

[KingLT1]

Originally Posted by cmitchell17

But do we have options for raising compression besides the usual mill .030 from the heads? Without getting into serious money and complete engine builds with pistons of course.

Thinner head gaskets?

Originally Posted by Nabush

On my end I don't have stock cats and stuff...


- Ported MSD
- Ported 95mm by Solers Performance
- ARH 1-7/8 Headers and X pipe


I decided to buy a full Katech Stage 2 engine and sell mine in parts. I know the engine Katech sells me makes 600HP/530 FtLbs on pump gas. It has a smaller camshaft ("Torquer LT1 cam") but it keeps VVT so it makes torque everywhere, which is the best for my application (Roadcourse and AutoX). I also believe more their experience as far as valvetrain than TSP, as they do extensive durability and studies with their spintron valve test cell. They also have real racing experience.

I'm tired of spending so much time figuring out the issue...Having a peaky engine is fun in a way but not efficient enough for my use.

There is a reason why the big 3 OEM's use PD superchargers on all their flagship cars...JS!

[6spdhyperblue]

Do they include a tune?

[oldman]

I'm sure Katech does (or at a least a way to address it), they are a top shelf engine builder. I used Rynne Cunningham for my remote tune (super good), many good tuners that are sponsors here also.

From post 81:

Oldman wrote: I like the Katech, but the LT4 manual is a little more aggressive, I don't think you can go wrong with the torquer, I like the Cam Motion more for longevity and gentle ramps but it will leave a good bit of power on the table vs Katech's LT4 grind.

Don't advance the cam a notch.

Katech torque cam : 219 / 233 @ .050, . 643/ .655 lift, 118 LSA (only NA application with spces)

I really don't like the idea of FI on a roadrace / autoX car. You don't need the weight nor the heat and its associated longevity problems.

Make sure you tell then you want the Johnson lifter: https://store.katechengines.com/cams...-parts-c4.aspx

I'm green with envy, wish I could afford something like a Katch engine in a C7 or 1LE....