Hey everyone! So I found out I fried my piston rings today in my l98 because it is burning oil terribly and I have wayyy too much blow by. Well I built the top of the engine and just knew automatically that I was going to need an upgraded rotating assembly. I just thought I would run the set up I had until It blew, so I had a 350 bored .030 over for a 383 and now I've just been waiting for this day. Now I just sort of want to hear everyone's opinions here. Here is my top end set up:
AFR 195cc Heads
1.6 Roller Rockers
Edelbrock RPM intake
Holley Sniper EFI
Hooker short tube headers with a deleted cat
Now I want everyone's opinion on how I should build my bottom end if my goal is roughly 500 HP. I was thinking:
LT4 hot cam
Roller Lifters
Eagle 383 rotating assembly with 6.000 connecting rods.
The rotating assembly I am on the fence about because I am not sure if I need forged everything or not. The difference in price is close to $800 so I just am not sure if forged is necessary for what my goal is. Im totally open to suggestions though as to if you all think I need forged. I definitely want the 6.000" connecting rods due to the fact that they will be easier on the block. And before an LS is suggested I just had the bored out 350 before I bought this car so I figured I would put it to good use. LOL. So does this sound like a good game plan or largely a bad one?

 

No you don't need forged everything, I am running forged everything in my 398 but no you don't require it.

 

I don't think you'll get to 500hp with the hot cam.

Probably need over 230 @.050 for that.

 

Would you recommend a comp cam?
or something like this:
https://www.summitracing.com/parts/t...oaAn4IEALw_wcB

 

Comp cams are petty good yeah. Crower, etc. Lots of good companies.

 

Don't believe you need forged internals, If you were looking for more horsepower and rpms then the forged assembly would be preferable. Like others said the key is a good cam and maybe a switch to equal length long tube headers and a true dual exhaust system. 1.6RR are a must for that little extra 5 or 6 horsepower over 1.5 or non roller arms. Cheers, J

 

Minimum 230 at .050 duration. As stated above. 11 to 1 compression DCR will work fine on the street too. Long Tube headers, 52mm Throttle body.. And your heads are fine.

 

What Lobe Separation angle and what lift would you suggest? would something in the .525 intake .525 exhaust range? Thanks...

 

We really need to know how you plan to use the car. The cam is the issue here. The rest of the build is probably fine, although I'd go with long-tube headers. Also, do you mean 500rwhp or 500hp at the crank?

The hot cam isn't what you want, and it won't make anything close to 500hp at the crank, much less at the rear wheels. Also, you need the AFR 195 Comp heads, not the street heads, or else you'll need a stupid cam to meet your peak power goal. My 396 with a ported LT4 intake, heads very similar to the AFR 195 Comps (but definitely better at low lift), and a Comp Cams XFI custom cam using 218/224 lift at 050 and .570/.565 lift on 1.6 rockers with 110LSA made in the range of 420rwhp (so high400s at the crank, but not quite 500hp). It was pretty fast - most people thought it way more power than it did - and it pulled well from midrange on up. It was still quite docile and I daily drove that car for two years, drive-throughs and all. It would pull on stock C6 Z06 and just got nosed by a 2022 GT500 and Lambo Huracan, so that means it would trap around 130mph, which is way faster than most people realize.

To get an honest 500rwhp, the 230 duration mentioned above is probably the minimum, but you are going to sacrifice a ton of drivability and midrange power just to get that peak power number. My friend had a C5 track car with an LS1 that dyno'd around 475rwhp, but it had a way more radical cam than mine to get that power. It was fast above 5000rpm but it felt broken below that. For most purposes - including autocross use - my car was better and faster. IOW, be careful what you wish for.

 

My purpose with the car is just to have fun with it. I have a line lock installed and am probably going to ZF 6 speed swap it while the engines out. I already have my Jeep CJ for car shows and such and my daily driver truck, so my plan is just to have some fun and do some burnouts from time to time. I want to take it to a strip atleast once to see what it will run. Other than that it is more of a summer time toy. What cam specs would you suggest? Oh also, 500 HP at the crank is my goal.

 

I meant to ask one other question: what axle ratio does your car have? My 96 had 3.45 gears with the ZF6 and if I'd had any more cam I would have wanted 3.73s or 4.11s. In fact, the previous owner of my car (MSR here on this forum - he built the engine) originally had a more radical cam and took it out because 6th gear was useless under 80mph or so: the car would buck.

Also, I'm not sure of using that Edelbrock RPM intake. I would look for a MiniRam or maybe the Edelbrock Pro-Flo XT.

So again, if you get the proper AFR heads (195 Comp) and use the cam spec I had and use good long-tube headers, that's probably good for 480ish at the crank and the car should be extremely fun to drive on the street. It will break true street tires loose in second gear on a roll and will also run fine when you lug it down to 1500rpm (e.g. 6th gear at 60mph). If you really have to have 500hp at the crank for some reason, then you'll need to crack open the Comp Cams catalog and go with whatever the next step bigger cam lobes are from what I used (my lobes were XFI catalog numbers 3014 and 3035). But you'll need 3.73s at least and you'll lose some midrange, so the car won't be as fun to drive around the street. I really think you should try to ride in a legit 400rwhp C4 before you decide that you have to aim for a certain peak power figure. Unfortunately, there aren't many around that were done properly (with good heads and intake). I sold mine or else I'd invite to come visit and see what it's like. Try a current-gen Camaro ZL1, which isn't quite as fast as my C4 was but it's close. If that's truly not fast enough for you, then you need to buckle up because your life is about to get harder!

 

Matt since you're in here, can you recommend a cam for a 383 in a 1991 ZF6 with AFR street 195 heads, 10.7:1 compression or so, and a miniram intake? Purpose is a track car for my local time attack series (~10:00 sessions) but that also can hold its own on the highway. Goal is 390-405rwhp or so. Crank is a scat 9000 stroker, rods are forged eagle, pistons are forged icons.

I believe the heads max out at 0.600" lift but flow levels off at 0.550" and 6500 RPM or so

Hoping to use the factory ECU with a tuned chip.

Thanks man!

 

I'd probably still look at the exact same cam I used (Comp Cams 3014 intake and 3035 exhaust with 110-degree LSA, installed straight up). It would get you probably 380-390rwhp with your parts, but would give you lots of midrange and possibly more average power through the gears than a cam with more duration. It would also be a great cam for highway and fun-street use. It will be nice on track because you'll have more flexibility on gear selection due to the flatter torque curve; and you won't need to run it beyond 6500rpm (maybe 6200rpm) to get all of the power curve, which is nice for engine longevity. I would still run it with 1.6 rockers, because even if the heads max out their flow at .550" lift, they will be at that max flow longer with the valves opening at .565/.570". These lobes have pretty steep/aggressive ramp rates, which is great for power. You will need to spec a good valvetrain. I had Jesel rockers, which was way overkill (it was spec'd for the much bigger cam and higher RPMs), but maybe ask Comp Cams what rockers, springs, and seat pressures to use with that cam.

BTW, with that cam in my 396 and the speed/power it could generate, I drove that car to Bowling Green to the Corvette Museum (~300mi) twice and got 25mpg on the trips. This is the same C4 that runs with new GT500s and Huracans without power adders. With the street AFRs and 13cid less displacement, you'd be a bit down on power from my car, but not a ton. I had about the same CR as you: the previous owner had hoped to get 11:1 but got about 10.8 when everything was measured.

PS - I don't know about tuning your stock ECU. My 94-96 PCM was completely different. I expect that if you can get the chips burned, it can be calibrated to work with this setup, but it might take a lot of iterations of the calibration to dial it in well.

 

112 to 114 is fine. 525 lift with 1.6 rockers is a bit low. You are going to need to be 550-575 lift.
Its very streetable with an automatic and 2500rpm stall.
Not sure what head gaskets are recommended now adays, but the LT1s had a gasket from the Impala SS LT1 that raised compression little. That will help compensate loss due to AFR heads
Lingenfelter had some high lift short duration cams with 112 to 114 lsa, hat did very well in 383/396s. Very hard to beat an LPE car.. Very well tuned cars too. Very well tuned.

 

Matt are you talking about a custom grind cam or the Comp XFI 218/224 0.570/0.565" lift, 113 LSA cam?

I already have an LT4 Hot Cam which is 218/228 and 0.525/0.525" lift, 112 LSA

I don't mind missing the peak rwhp goal by 10hp if it means better drivability and better average hp output at lower RPMs.

 

Spend some time modeling the engine with software such as Performance Trends Engine Analyzer, and it has on “optimize” function for lift and duration. Also it’s interesting to see the effect of the exhaust system, once you’re above 400hp or so.

 

I have driven a Hot Cam in a 383, C4 auto. Very tame camshaft. Very mild. If you take a Hot cam, which is spec'd for 1.6 rollers, and put 1.5 rollers, you will be amazed at the similarities in size ( lift) it is to a standard LT1 camshaft. Not the same, but very close.

 

Mine was a custom grind with off-the-shelf lobes but a tighter LSA of 110 degrees. The one you reference might even have the same lobes, but the wider LSA will move the powerband upward a bit whereas the 110 LSA will concentrate more power in the midrange. My friend who built the engine also had a hypothesis that the great overlap provided by the tighter LSA worked well the short runners of the LT4 intake (and Miniram). That's what I would go with again if they don't make a regular XFI268 with 110 LSA.

I know that sounds close to what I'm talking about, but it's really not. As AmoriFati said, it's really very tame. The thing is that with the much lower lift values and much milder ramp rates, the valves spend a lot less time in the higher lift range where the heads flow best. The overlap is also a lot less: even if the duration and LSA were identical the overlap will be less with lower lift. It's just not nearly as potent a cam. You would be missing more like 50hp, not just 10hp; and the average power would also be a lot less, probably an even bigger difference than the peak power. The extra overlap and aggressive ramps of a cam like mine will really make the midrange jump, which is where you'll find better average power and more flexibility of useful RPM on track.