2seater

Power curve vs drive ratio

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2seater    116

       I started a different thread only to move this information from the tire size discussion. This is a better hp curve comparison for the '88-90 vs '91 engines as I found I could overlay the curves for easier comparison. As stated in the other thread, the '88-'90 curves are identical, which just cannot be IMHO. The acceleration clearly goes flat well under 5000 rpm on the '89-'90 in my experience, and when I installed an '88 cam in my '90 engine, the rpm range was extended. The point of this post is simply to theorize that the '91 has a different final drive ratio to better match the performance envelope of the engine. With the curves overlaid, it is plain that the LN3 has more power below 2500 rpm and actually regains the advantage above 5000rpm, but my opinion would only be the '88 engine.

88, 90 and 91 hp curve comparison.png

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DAVES89    339

89RDG wants me to do a "dyno" test. I have changed the oil and if 2Seater wants to meet up with me I would be happy to see what if any increase I have gained.

 2seater you have my number, give me a call... 

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89RedDarkGrey    252

2seater- would there be a difference between the 440T4-4T60 and a 4T60E? Also- did '89-'91 use the same 3800? What year did the 3800 II come out (split intake)?

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2seater    116
37 minutes ago, 89RedDarkGrey said:

2seater- would there be a difference between the 440T4-4T60 and a 4T60E? Also- did '89-'91 use the same 3800? What year did the 3800 II come out (split intake)?

I don't know if there is any strength difference between the hydraulic and electronic versions, but I am pretty sure the transaxle continued to evolve and later models had improvements when weak links were discovered. I just don't know much about the details.

 

I don't understand the reference to split intake? The tuned port style came out first on the L27 (Series I), made of cast aluminum, in 1990, but was only available in the Regal. The Reatta got it the next year in 1991. Many of the engine parts are interchangeable, however the crank is different due to the one piece seal, also the rear block machining for the seal assembly. I think the balancer is different as it is a press on, probably due to the future availability of the supercharged version. The camshaft also has a different retaining system on the nose and no thrust button. The heads are the same except for an approx. 5/8" hole for the internal PCV system (easily added). I am using the aluminum tpi manifold on my '89 engine and simply added that hole in the head, actually it's tapped for a pipe plug so either style intake manifold can be used.

 

The Series II is a different animal, came out in '96 I believe. One inch shorter deck height (approx. 8.5"), so totally different rods and pistons. Better heads that "might" bolt on but different valve order.

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2seater    116
2 hours ago, DAVES89 said:

89RDG wants me to do a "dyno" test. I have changed the oil and if 2Seater wants to meet up with me I would be happy to see what if any increase I have gained.

 2seater you have my number, give me a call... 

   Maybe we can get together when I get my car out, so I can setup to finish the accumulator and switch testing. One thing after another seems to intervene.

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89RedDarkGrey    252

Thank you for that explanation. I got the 1 and 2 mixed up.:blink:

 

53 minutes ago, 2seater said:

I don't understand the reference to split intake?

 

https://en.wikipedia.org/wiki/Buick_V6_engine#Pre-Series_I

 

Contains some interesting info near the end of the paragraph, and into the next section(s)

 

https://en.wikipedia.org/wiki/Buick_V6_engine#Series_I

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2seater    116

Oh, now I understand. Yes, the L27 tpi manifold is a two piece design, upper and lower.

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2seater    116

This is completely frivolous, but interesting to me. This is a chart overlaid with the 1987 GN, LN3 and '95 L67. It was a bit of a surprise the LN3 appears to hold a tiny advantage at the initial launch vs the S/C engine. Interesting the shape of the torque curve between the GN and LN3 is similar, although light years apart in magnitude :)

 

 

GN vs LN3 vs L67.png

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89RedDarkGrey    252

+12k RPM to gain only 65 ft-lb of torque? That's strange. It's got to be the '88 cam in play, able to nearly keep up in lower end. The GN makes the others look like Pintos in comparison:lol:

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