This custom Reatta needs to be reality

[scourge]

This custom Reatta needs to be reality:

Its not like 20 years ago. So many IRS available for the C4 Corvette to the Cadillac CTS and 300hp V6s make projects like this far more affordable and realistic than ever. 

[handmedownreatta]

21 hours ago, scourge said:

This custom Reatta needs to be reality:

Its not like 20 years ago. So many IRS available for the C4 Corvette to the Cadillac CTS and 300hp V6s make projects like this far more affordable and realistic than ever. 

i don't care for the wheels.the allante had a 300 hp northstar.i suspect the engine cradles of the allante and reatta are similar.

[D-a-n-i-e-l]

12 hours ago, handmedownreatta said:

i don't care for the wheels.the allante had a 300 hp northstar.i suspect the engine cradles of the allante and reatta are similar.

That engine is far less reliable than a SC 3800, and the 3800 can easily produce 300+. With less cost and less loss of the Reatta's functions.

[dship]

12 hours ago, handmedownreatta said:

i don't care for the wheels.the allante had a 300 hp northstar.i suspect the engine cradles of the allante and reatta are similar.

I'm not quite sure that the engine cradles would have been similar.  The Northstar was a V8 vs. Reatta having a V6.  1993 was the last year of Allante production and the only year with the Northstar V8.  Prior years the Allante was equipped with the 4.5L V8.  Just saying...

Edited February 2, 2019 by DShip (see edit history)

[padgett]

And later interesting Caddys have gone  to RWD.

['91 Polo Green]

I do realize it is an old post - but can anyone direct me to the specific info on beefing up the horse power on the '91 L27 engines? Thanks!

[Barney Eaton]

On the image......lowering the Reatta is problematic because of the suspension.   In the attached generic suspension picture,  note if you go too large on the wheels, the tire will rub the bottom of the spring mount.

That is the limiting factor when it comes to tires..........however you can put spacers behind the wheel or change the backspacing so it will clear the spring mount,  however that will probably cause the tire to rub the fender.

 

On the engine......the quick way to get the HP is to transplant a later 3800 supercharged engine and transmission.......you must use the transmission so it will handle the supercharger HP

Staying with your stock engine,  you improve getting air IN and OUT.

On the OUT side,  the firewall side exhaust header is not a great design.  I don't know if anyone makes a direct replacement that flows better, but look at the picture and you will see there is excess material where the pipe exits the header.

several owners have ground that away with a die grinder,  but that alone will not give you big improvements.    Porting the heads would probably help.

reprogramming the ECM chip for a little more advance and shift points would be noticed but you would probably need to go to premium fuel.

I know "twoseater" in Wisc.  has done lots of engine work and hopefully he will jump in and add his comments.

[Chrisssssssss]

An SC3800 swap is in my future dreams. Bought a 98 Buick Regal GS as a donor car and when it finishes falling apart, I will gut the engine and trans for the Reatta...

 

[D-a-n-i-e-l]

6 hours ago, '91 Polo Green said:

I do realize it is an old post - but can anyone direct me to the specific info on beefing up the horse power on the '91 L27 engines? Thanks!

94-95 supercharged engine from a park avenue ultra.

[B Jake Moran]

9 hours ago, D-a-n-i-e-l said:

94-95 supercharged engine from a park avenue ultra.

What if a person wants to stay naturally aspirated?  I am not talking about a huge bump in performance but just eeking out what you can.  Not the like the old days when a guy would put on more carb cfm and headers and gain 20 to 50 hp.  It's my understanding the Reatta 3800 already has "roller rockers" and decent valve openings but I wish I could buy a "performance" cam for it that might add 10 hp and improve the exhaust flow by 5-10 hp with a stock appearing muffler.  That's about all I think you can do.  But that would gain 25 hp maybe?   I just have never heard of a "performance" cam etc offered in the market.

[D-a-n-i-e-l]

17 minutes ago, B Jake Moran said:

What if a person wants to stay naturally aspirated?  I am not talking about a huge bump in performance but just eeking out what you can.  Not the like the old days when a guy would put on more carb cfm and headers and gain 20 to 50 hp.  It's my understanding the Reatta 3800 already has "roller rockers" and decent valve openings but I wish I could buy a "performance" cam for it that might add 10 hp and improve the exhaust flow by 5-10 hp with a stock appearing muffler.  That's about all I think you can do.  But that would gain 25 hp maybe?   I just have never heard of a "performance" cam etc offered in the market.

Not so much for our version, but they are available for the series two and three NA engines.

[Ronnie]

The cam in the '88 models is reported to be a little better than the cams used in later models.

[Barney Eaton]

I believe it was at 2008 Flint roundtable, one of the engineers said the transmission shift points were programmed more for a luxury vehicle than a sports car.

That is probably why the transmission are so trouble free.   Maybe a "shift kit" would pep up the cars some..........on the 1991 with an electronic transmission,  that can probably be done by reprogramming the chip in the ECM   

[DAVES89]

When I had an engine rebuilt for the Red on 2seaters advice I used an '88 cam and higher compression pistons. Then a little porting on the exhaust [including the end piece as Barney advises]. I believe I picked up about 40 HP which doesn't overwork the transmission.

[2seater]

As Daniel points out and Dave confirms, you need to get into the engine internals to find -anything significant. The engine uses roller lifters but the rockers are conventional sled type. Opening the exhaust outlet as pointed out is cheap to do but not easy to access unless removed first. It even seems to sound a bit better and deeper tone too. A cone type air filter certainly sounds faster 😛. The stock muffler isn't terrible from a flow perspective but if replacing, a straight through type does flow better. While not recommending removing the catalytic converter, just about any cheap modern replacement cat flows better. The last two items sound more powerful, like the intake, but taken together, they do increase the potential for the engine to breathe. The cam can be reground but I do not know of any aftermarket support for the Reatta available engines. That said, the '88 cam does have measurably greater lift and duration, but are pretty much unobtanium. The Clevite part # 229-2211 is the correct replacement cam for the '88 if you can find one, and is a direct bolt in. One item I have found, when replacing the timing chain set is to use the factory style Morse brand chain for long term durability. It costs significantly more, but the commonly available Cloyes chain will act just like a saw against the tensioner due to the side plates riding high relative to the chain link material.

[DAVES89]

Hey Hal what compression do these engines have and what did you recommend to me?

 Also one thing that is not common knowledge here but was discussed in some length on Ronnie's forum was that I found a 1988 engine that had just over 5000 miles on it. We [Hal, Kendall, and myself were amazed at how clean and new everything looked. So for very little cost I got a good performance upgrade and didn't have to mess with reprogramming chips, looking for adapter parts, and changing any sensors. A stock engine with a little more power!

['91 Polo Green]

Rhetorical statement - and sorry to butt-in; So '88 engines offer better performance than say a '91 engine. (I'll take my answer off the air)

['91 Polo Green]

Well I'm an idiot! I have gots to stop replying to post without reading them. DagNabbit!

[2seater]

This is a comparison of the power curves between LN3 and L27. More down low power for the early engines, and to complicate the "feel", the later engine works with a lower gear ratio and taller tires. No idea of a direct head to head test, but my guess would be the early engines would jump off the line better but would be outrun by the later engine after a bit. Anyone have both to do a comparison a few times🤔

[2seater]

18 hours ago, DAVES89 said:

Hey Hal what compression do these engines have and what did you recommend to me?

 Also one thing that is not common knowledge here but was discussed in some length on Ronnie's forum was that I found a 1988 engine that had just over 5000 miles on it. We [Hal, Kendall, and myself were amazed at how clean and new everything looked. So for very little cost I got a good performance upgrade and didn't have to mess with reprogramming chips, looking for adapter parts, and changing any sensors. A stock engine with a little more power!

Stock the compression ratio is 8.5:1 per the FSM, and from my actual measurements that is pretty accurate. The later L27 replacement pistons I suggested are good for right at 9:1 using the stock OE style headgasket. Without machining the block, the piston is @ zero deck, or flush with the top of the block on compression. 

[wufibug]

Daniel, is the  bottom end of the "94-95 supercharged engine from a park avenue ultra" the same as our motors or did they have mods [cam, roller rockers etc] that , together with the supercharger increased performance?

[D-a-n-i-e-l]

On 8/2/2019 at 6:53 PM, wufibug said:

Daniel, is the  bottom end of the "94-95 supercharged engine from a park avenue ultra" the same as our motors or did they have mods [cam, roller rockers etc] that , together with the supercharger increased performance?

I did a full longblock swap, but on the series one SC engine (91-95) the blocks are identical. The cranks are different, I don't recall if the cams have different profiles or not.

 

[2seater]

I have a '95 L67 on my engine stand but I haven't opened it up to see what may actually be different. I do know some of the part number differences between cranks, rods pistons etc is due to things that may or may not actually be higher performing. For example, in '91, the engine changed to a one piece rear crank seal, requiring the crank and block to be machined differently. Some later models have floating piston pins which are different rod and piston part numbers, and may or may not be stronger. I know a roller trunnion rocker appeared somewhere in the '93 and later time frame, but they won't swap into the earlier engine. I am not sure about cam profiles either, but in general from what I have seen, the cams are actually what would be called milder. In any case, most will not swap backwards into the earlier engines. The bearing diameter is larger and use a different cam retainer system.