Rocker arm swap

[ChrisWhewell]

Please correct me if mis-reading the link below, are the rocker arms on a 90 Reatta LN3 the same as those on a 1995 VIN K motor  ?

 

In this article, the gentleman mentions that:   "All references to SI are taken from a 90 Vin C 3800 and all SII are in reference to a 95 Vin K 3800 engine

 

And it also states:  "you know the SI and SII use the same lifters? "

 

I'd really like to find some 1.8 ratio rocker arms I can bolt into my LN3.   If its true that the 90 LN3 rockers are the same as those on a '95 VIN K motor, that might help.   Thanks !!

 

http://forums.motorswap.org/viewtopic.php?t=1663&sid=842a00ed0234bc1a22806ea212a65664

 

 

 

 

Edited September 16, 2016 by ChrisWhewell (see edit history)

[ChrisWhewell]

Yeah, I was reading it wrong, the rocker arms aren't the same.   Oh well, its an educational article nevertheless.  

 

I can't seem to find any decent performance upgrade for an LN3... anywhere !!!!!!     A little more lift would make a noticeable improvement, did on my vette anyway....   I bet Comp could sell quite a few sets 1.8 ratio roller rocker arms for LN3 

[ChrisWhewell]

Here's a thought:

 

http://forums.motorswap.org/viewtopic.php?t=2422

[2seater]

You can't find anything for the LN3 because it doesn't exist, and likely never will. A custom new or reground cam will help or a stock '88 cam has a bit more potential too. The trans. in your '90 is the best of the hydraulic transaxles, with all of the updates that have been done over the years, but if hot rodded, will have a shorter life. The L67 swap is done because it works.

[handmedownreatta]

On 9/16/2016 at 1:35 PM, ChrisWhewell said:

Here's a thought:

 

http://forums.motorswap.org/viewtopic.php?t=2422

he couldn't even report the track results?i think something broke.

[ChrisWhewell]

Yes, is has a funny "sniff" to it.   I think someone would be proud of having such an accomplishment, plus it would be an advance in the art.   Providing a write-up at the most would take 15 minutes.  I'm amazed at how little is available in the aftermarket for LN3.  One might think by now Gale Banks or someone would have put out a turbo kit

[2seater]

Many years ago I was looking for upgrade stuff too. I contacted a couple of them, ZZP and Extreme I think? One reply was "Why?" The engine only had a 3-4year run in LN3 form, and was in pretty much constant transition from '85 or so when the first fwd models came out. It sort of stabilized with the Series I in 90-91 until the Series II in 96? but there were still differences within the family. Not so good for an aftermarket supplier. That is pretty much why I embarked on my turbo experimenting. There just wasn't anything available and even if there was, what would fit under the hood of a Grand Prix, a Bonneville, Regal, etc.. probably wouldn't fit in the Reatta. The factory did several different turbo builds almost three decades ago, and they all worked, but was never pursued before the Reatta died. There likely would have been a S/C model had it continued and the L67 spread across the GM models during the '90's. The closest thing to a plug and play substantial upgrade is an OBD1 L67 swap. I know the transmission is always looked upon as the fusible link, and if abused, it likely is. Like most mechanical systems, there is only so much capacity per rpm available. If driven with some restraint and let the speed/rpm come up a bit, the trans. can handle more than if hammered from a dead stop. Just my $0.02

[ChrisWhewell]

I think that's all true.   I also think the trans in our Reattas are probably good for 225 HP, tops.   So an upgrade to 210 would probably be safe.   Not a huge advance, going from 165 HP to 210, but an advance nevertheless.  Probably accomplishable with a head swap having larger valves and bigger injectors

[2seater]

It doesn't sound like a lot, but percentage wise, it is a pretty big step. I know it sounds pretty tame compared to more modern vehicles, but the Reatta is too heavy to be a race car, so you take what is reasonable. The bigger effect from a boosted engine is the greater increase in torque, which helps get it moving, and therein lies the potential for overload. Adding the S/C top end to the existing engine can be done, not unlike turbocharging what you have, but probably entails as much work as a complete swap. I know in my case the turbocharging is intentionally limited and designed with a certain amount of lag to allow the rpm to increase ahead of the power. I do it as a thought experiment and I enjoy seeing the result, sometimes successful, sometimes not. Your results may vary

[handmedownreatta]

i have to wonder how much horsepower you could add with the sc top end with the computer compensating for it by using a smaller pulley.

[2seater]

• I must admit the details of the tuning are outside of my pay grade on this install. It has been done successfully, no matter if a complete engine or just the S/C, as the ECM has been decoded for the S/C tune so the info is available. Some do not use EGR and I believe the years that do are a different style, so that likely has to be turned off. The MAF chart extends to 170 gm/sec (10.4kHz) and I have seen as high as 172 on my very low boost install (stock '90 engine with '88 cam), so that calculates to somewhere around 225 hp. That is probably somewhat optimistic, but someone with an S/C installed could comment on what they see for a maximum. I know Ryan @ GM Tuners can do a chip for it for not a lot of money. There is another option if you run out of range, and that is the 3" inline mounted MAF available in the U-Pick yards that has the exact same frequency range but approx. 50% greater flow within that range. That is something I hope to quantify this winter as a flowbench project for my higher boost install since that turbo install maxed the MAF very quickly and led to tuning issues.

[ChrisWhewell]

Good job on being such a pioneer, I salute you for sure.  That's Americanism, love ya bro

[jonlabree]

Two years ago when I Dyno'ed my Reatta it turned out 391hp at the flywheel. That was before I redid the bottom end with a GN crank and 96 piston and rods.

[ChrisWhewell]

Wow, what transmission are you using ?  what rpm was the 391 HP at ?

[ChrisWhewell]

6 hours ago, 63viking said:

Two years ago when I Dyno'ed my Reatta it turned out 391hp at the flywheel. That was before I redid the bottom end with a GN crank and 96 piston and rods.

At least you aint proud about it   https://www.biblegateway.com/passage/?search=Proverbs+6%3A16-19&version=KJV  

 

[handmedownreatta]

2 hours ago, ChrisWhewell said:

At least you aint proud about it   https://www.biblegateway.com/passage/?search=Proverbs+6%3A16-19&version=KJV  

 

if it has nitris?AND a supercharger it could have 391 hp.

[2seater]

With something over a +100 shot it is possible.

 

I have heard of this "build" before and I can't make the numbers come out right but maybe I am missing something? I never received the details I asked about at that time. Perhaps with some machining, or a special flexplate and torque converter, the GN crank may fit and there is a .225" stroker available, but even if those items are in place, the '96 engines are all Series II which has a much shorter deck dimension, something like 1.0" less, so the rods and pistons are all too short for our 9.5" deck block? The only way it sort of works is using the early rods, which are about 6.328 long, the 1.197" compression height '96 s/c pistons and the 3.625" stroker crank for a total around 9.338", so over .100" down the hole for a pretty low compression ratio. Might work good with a bunch of boost and/or nitrous. I am not sure the stock GN crank is stronger than the stock LN3 crank, it has the same rolled fillets, but an aftermarket crank probably is. No comment on the rest.

[ChrisWhewell]

16 hours ago, 89RedSlate said:

 

This is his car

Kick-A !!!   That's the coolest Reatta I ever saw !!

[jonlabree]

Two years ago when I Dyno'ed my Reatta it turned out 391hp at the flywheel. That was before I redid the bottom end with a GN crank and 96 piston and rods.

 

Any one interested in the details end a request and I might tell some of them.

FYI  It ran a 11:87  at 121 mph at Union Grove Il (with slicks)

 

 

[2seater]

Stout numbers for sure. Was the 1/4 mile after the additional changes? It would need more hp. or lighter weight for that sort of performance number.

[jonlabree]

It should run low 11s on paper.

I can always get more HP = more nitrous & Menthol/h2o. 

 

Oh, and by the way my error they are 95 pistons

Edited September 22, 2016 by 63viking (see edit history)

[ChrisWhewell]

I'm just wondering what transmission is in that thing !!   If it was a factory SC, that would seem to imply that the Hydra-matic division was holding something back from production ??   !!     Remember, the 93 model year Cutlasses with the 3.4L had to have the engine de-tuned b/c the 4t60 could only reliably handle 215 ft lbs of Tq !!    

[2seater]

Ahh, that calculates out better. Thanks for clarifying. The '95 S/C engine was still Series I, the '95 N/A engines had the lower deck.