Stock LT1 cam options
 

LT1 guys. I'm doing a ZF6 and Dana44 swap on my '94 over the winter. I need to fix some oil leaks (front seal I think) so I was thinking of doing a cam while in there. I'm not really interested in doing any head work, other than springs for the cam.

Was curious if anyone had any modern Stock LT1 cam combos to share.

If I can get 350+ hp out of a cam only I'll be fairly happy.

I think the stock LT1 heads flow around 220/160 at .500s lift so they should really be 400hp capable I'd think.

-- Joe

Nobody seems to venture too far from the norm, but I'd like to see somebody try a 108 lsa with moderate duration, some thing like the smallest bootlegger:

http://www.lunatipower.com/Product.aspx?id=8679&gid=403

Lunati claims a 40 hp gain over the hot cam in their catalog (pdf) for the big-un XX08240HR but that's a 240/252 duration cam.

Hey Pat,

That might be kind of aggressive...

I was kinda hoping for something that made 350+ hp but idles near stock and doesn't surge at low RPM with the manual.

(I know I know, LS swap lol)

-- Joe

Hey Joe. I hear ya, but almost anything can surge.

A hot-cam is said to be worth 20 hp on an LT4, so a 50 hp gain is a tall order for cam-only LT1.

My other car (Evo X GSR) with stock cams can surge like a b*tch under some situations such slowing and idling in gear, but some of it may be e-throttle and variable valve control related. Low gearing is also contributing factor, I think.

Example log:

https://datazap.me/u/tequilaboy/70-f...7974&mark=7758

Ratios EVO X: Final drive drive 4.687:1 1st Gear 2.857 2nd Gear 1.950 3rd Gear 1.444 4th Gear 1.096 5th Gear 0.761

I'm half tempted to build a bracket and pick up a powerdyne, but finding a reverse rotation for the LT1 would be quite difficult. It's nearly impossible to mount a blower on the passenger side of the LT1 and not run it backwards.

That and I'm not sure how I'd retard timing under boost with the factory ECM.

But I'd be able to run a stock cam and just deal with boost fueling..

Then again, a blown 10.8:1 compression motor might not be a fantastic idea lol
-- Joe

Funny, I had a reverse rotation Powerdyne years ago, but sold it to a guy who was planning to install it on a Lexus SC400. Sorry for going a bit off-topic.

Does anyone make reverse rotation impellers for them?

A BD11A would fit perfectly on the passenger side turned around. I could make brackets in an hour.

-- Joe

928 has a BD-11R scroll for sale, and here's an impeller:
https://www.ebay.com/itm/XB1A-Billet...-/264011142039

I like the idea...but getting expensive fast, since you would also need a good BD-11A drive unit.

A geared XB1A with a standard impeller and scroll mounted backwards would be another (pricier) option since the output shaft spins opposite of the input. Maybe a TQstorm unit if they are still around.

I would need a CCW though (when looking at the pulley)

-- Joe

Yes, I know. Can be confusing to think about and discuss. The BD-11R and XB1A volutes both use a CW impeller (when facing the inducer), more on the pulley side later. In contrast, the standard rotation BD-11A has a CCW impeller (and volute) with a CW pulley rotation.

So with a BD-11R mounted backwards, the pulley would rotate CCW (which is what you want) and the impeller would rotate CW and make boost.

With an XB1A mounted backwards, the pulley would still rotate CCW, but the impeller would also rotate CCW due to the gear drive, so I think a CCW impeller and volute set could be swapped from a standard rotation BD-11A and make boost. Due to the complexity of buying a lot of parts and mixing and matching, this may not be a cost effective solution.

You asked for modern combos and mine is not but ... on my stock 95A4 we gained just over 40 RWHP increase on a mustang dyno from the "old" LT4 hot cam kit, HD timing chain & sprocket kit, all new ignition components, long tube headers and a tune. from 254 to 295 rwhp. Nothing was done to the stock heads or intake manifold.

I know that's not the level of increase you're looking for. My instructions to the tuner were for "guaranteed livability in commuter traffic" rather than peak HP. This was 70K ago and the car has never stalled.

I see. I'm so used to Vortechs at this point.

The thoughts about a BD11A is because they are kinda cheap, often around $500 for a head unit. If I could get a $400-500 impeller that is direct bolt up, I'd do it. But if I have to change the scroll too, it adds up as you suggested.

I like the belt drive on lower HP stuff.

But all in all, the cost might far exceed a C/H swap, so maybe back to just the cam.

I know guys used to do the cc306 cam, but that was just a nasty bitter cam with a ton of overlap. Wasn't sure if there was a 'middle ground' cam.

LT4 "hot" cam is 218/228 and .492/.492

I have some comp pro mag self aligning 1.6 rrs on the shelf, so I could do a cam and springs and headers.

-- Joe

Lots of cam+bolt ons F-bodies in that RWHP range, but nowhere near stock driveability. And the vette will dyno lower with the same combo.

A custom cam can get you a little more power for a given driveability, but for your goals NA you really need head porting. You don't need anything crazy - LE1 or LE2 level - and it's way cheaper than any FI solution you're now toying with.

I'm assuming we're talking about 350rwhp? If so, I agree with the others who say it can be done, but not with anything close to a stock idle. We've just been discussing this on another thread. This is especially so if no head work will be done (or, really, swapping to better heads altogether). The only way to do that with a stock-like idle is to head towards 400cid, either with a stroker kit or a 400 engine.

My cam follows this plan, except I'm running a 396 with heavily ported LT4 heads. It's the Comp Cams 3014 intake and 3015 exhaust (218/224 and .570/.573) on 108 LSA. It obviously has aggressive ramp rates (I would guess not advisable for stock rockers) and more lift than a stock head could probably use. It obviously won't idle anything like stock with the overlap, but at 1000rpm it is dead-nuts reliable and stable - no surging. It's perfectly streetable, and I get 25-26mpg on long highway drives. This is all in a 96 with a stock ECM and good tuning.

CHP not wheel. I figure a stock LT1 is about 300hp, if I can get 50+ out of a cam and not have it drive like my 1,000hp firebird I'll be pleased lol.

The thing that kinda boggles my mind is, on the flowbench LT1 heads outflow like Sportsman II's for example, which I never had a problem making 400hp out of a 383 and a comp 503 cam (224/230 .502/.510).

-- Joe

I don't want to rip the heads off. It's a driver, not a race car. I'd just like it to hang with C5's.

I was gonna sell the car and get a stock C6, but now that I have the ZF6 and Dana44 I just wanna do some basic mods.

Like I mentioned before, I have a blown 412" SBC in a firebird that cranks out almost 1,000hp. That thing is an animal on the street. Breaks the tires loose all the time, can't be driven in the rain.

-- Joe

Counter rotating cam ..lol. If you run electric water pump and a 2 gear geardrive it would work. Counter rotating engine requires a custom rear diff or flipping d44 upside down. It was a "Smokey" Yunick trick during his NASCAR days.
With" hot cam" you may get away without tuning since GMPP developed it and sold it as a kit for the LT1/4. GMPP didn't release a prom for 92-93, so ECM / PCM MAY be able to compensate for it. 94-96 LTx PCM use flash programming which can be a problem depending on where you are located. You could possibly have to mail PCM for tuning, wait for it to come back, then mail it back for tweaking, then wait, then mail....repeating until tune is acceptable. Tune could be on a flash drive however you have to a way to load it. You should consider tuning prior to changing cam. I would also stick to the more popular combinations to minimize tuning challenges.

I tune my PCM. While it's an antique vs the Megasquirt that runs my race car, it works out. I have a lot of minor alterations, emissions deleted, etc. Car has no EGR, air injection.

I'm not worried about tuning the car, I just don't want it to have no vac at idle, and be really surgey at low RPM with the stick. On an automatic car you can go with a crazy cam and loose converter and not notice any issues. It will just stall and grab. On a stick car, it won't typically 'lug' with a big cam, it will jerk back and forth when the stall saver functionality kicks in.

-- Joe

I dont see 350 at the tires with just the cam, youll need more. You could always leave the small valves, a moderate port job and let the #s be what it may. That cam be done without much damage to the wallet or time if you DIY. Would have to pull out a file of flowsheets I dont recall stock LT1 heads anywhere near 220 but its been awhile.

this summer we hauled a 96 w/lt4 motor to new braunsful as this shop still does dyno tunes on these cars. it made 362 whp and 379 rwtq before something went south at about 4800 rpms. it is a stock lt4 motor with the hot cam and 1 5/8 headers. no head work or any thing else done to the motor.