LT4 cam in L98?
Thread Starter
Drifting
Joined: Feb 2000
Posts: 1,917
Likes: 109
From: Crystal lake Il
2022 Corvette of the Year Winner -- Modified
2021 C4 of the Year - Modified Winner
LT4 cam in L98?
Has anyone tried an LT4 cam(stock) in an L98. What were performance results. How did it idle/exhaust note? I am looking to add more power to my 90 coupe without changing idle quality. Would 1.6 RR on a stock cam make much of a difference.
Lgaff
Lgaff
Pro
Joined: Mar 2001
Posts: 602
Likes: 1
From: Hacienda Heights, Ca. USA
Re: LT4 cam in L98? (lgaff)
I have put 1.6 roller rockers on a few of my vettes with the stock cam and yes there is a power improvement. Matter of fact I helped a friend install them on his '90. Don't know how much in numbers but you will feel it in the sotp. I will be installing an LT4 Hotcam in my '88 conv. in the very near future. I have the cam, springs etc. to install but I'll also be adding Hooker full length headers and a TPIS Bigmouth intake. I may have my heads CNC ported since I'll be in pretty deep in the motor. As far as idle quality goes, this cam does affect it and will require a new chip.
Safety Car
Joined: Jun 1999
Posts: 3,570
Likes: 3
From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
Re: LT4 cam in L98? (john25)
I would like to hear of the results also from someone that put a LT4 or Hot cam in an L98.
My guess it would either provide no improvement or hurt performance. The LT4 cam was designed for use with a short runner intake manifold and higher compression ratio to provide a flatter torque curve between 4000 and 5500 rpm. The stock long runner L98 intake manifold was designed for maximum torque below 4500 rpm, thus providing a restriction.
You may want to use a SuperRam or mini ram intake with the LT4 cam.
[Modified by Mez, 2:13 PM 8/24/2001]
My guess it would either provide no improvement or hurt performance. The LT4 cam was designed for use with a short runner intake manifold and higher compression ratio to provide a flatter torque curve between 4000 and 5500 rpm. The stock long runner L98 intake manifold was designed for maximum torque below 4500 rpm, thus providing a restriction.
You may want to use a SuperRam or mini ram intake with the LT4 cam.
[Modified by Mez, 2:13 PM 8/24/2001]
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Re: LT4 cam in L98? (lgaff)
With a good computer chip the idle won't be THAT bad. It's enough to notice if you know what to listen for, but the run of the mill ricer wouldn't. I have a dyno graph of what the hot cam with 1.6RR's did for my LT1 here, http://24.17.202.123/htmls/dyno_corvette.html
You'll notice the broad flat torque curve was uneffected, the biggest plus was the high end, it revs faster now and pulls hard all the way there. That's what makes me wonder about the L98, they just flat out don't breath at high RPM's, I don't know how much of that is the intake or the stock cam setup, but it is certainly worth doing the research before you do this mod. A cam that's good for top end power on a motor that won't turn past 5000 wouldn't be a good setup for you.
You'll notice the broad flat torque curve was uneffected, the biggest plus was the high end, it revs faster now and pulls hard all the way there. That's what makes me wonder about the L98, they just flat out don't breath at high RPM's, I don't know how much of that is the intake or the stock cam setup, but it is certainly worth doing the research before you do this mod. A cam that's good for top end power on a motor that won't turn past 5000 wouldn't be a good setup for you.
Instructor
Joined: May 2001
Posts: 123
Likes: 0
From: Hampstead,MD,US
Re: LT4 cam in L98? (lgaff)
Well..........
I'm going to go out on a limb here, and you can smack me if I'm wrong...
The LT1(4) engines. have front mounted, cam-driven, opti-spark distributors. That is to say that the timing gear end of the cam drives the distributor.. I'm pretty sure you can't put one in. Sorry, but you can probably get one with similar spec's..
Furthermore the LT series engine is a roller (low friction) engine allowing for a more changes in cam profile. I don't think the L-98 can support the speed of lobe profile change w/out a full roller conversion
I'm going to go out on a limb here, and you can smack me if I'm wrong...
The LT1(4) engines. have front mounted, cam-driven, opti-spark distributors. That is to say that the timing gear end of the cam drives the distributor.. I'm pretty sure you can't put one in. Sorry, but you can probably get one with similar spec's..
Furthermore the LT series engine is a roller (low friction) engine allowing for a more changes in cam profile. I don't think the L-98 can support the speed of lobe profile change w/out a full roller conversion
Instructor
Joined: May 2001
Posts: 123
Likes: 0
From: Hampstead,MD,US
Re: LT4 cam in L98? (lgaff)
Sorry, second note, if you're not planning on doing anything to wild to the intake and exhaust system, get a cam with more of a torquey profile, you'll see a noticable gain and it won't hurt your streetability much.
BTW, 1.6 RR's are a good idea and REMEMBER if you get them BEFORE a new cam factor that into a Cam decision
BTW, 1.6 RR's are a good idea and REMEMBER if you get them BEFORE a new cam factor that into a Cam decision
Pro
Joined: Mar 2001
Posts: 602
Likes: 1
From: Hacienda Heights, Ca. USA
Re: LT4 cam in L98? (89VetteWIP)
The LT4 Hotcam was designed to work in both the L98 and LT1-4. All you have to do is change the length of the pin for the cam gear for the respective motor. Keep in mind that my motor will have extensive mods to the intake system. It will not be stock and according to the desktop dyno will put out some pretty respectable numbers. I also spoke to Mike Osucha at More Performance and he says that this cam will work fine in an L98 with the proper valvetrain, which I have to go along with the cam. My exhaust will also be completely modified as well as having a higher stall torque converter. When it's all done I will have it dynoed and I'll post the numbers.
