For those that have experience and are very specific, could anyone share their thoughts on how the vibration "feel" of the 3800
and a stock 2.8 in the fiero differ?

I understand the 2.8 is a 60* engine design versus the 3800 90* design.

If the mounting is kept stock using FieroRoger engine mount design with either the 88 or pre-88 engine mount in place
on the cradle, should I expect a pretty much same vibration feel?
Using the stock rubber mounts at the for and aft transmission mounts for a getrag trans, and the V6 specific GM 88 engine mount.

It's understandable that once driving that vibration can go away and not noticable, but mainly at idle is my point.

Thanks,


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fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

[This message has been edited by fierogt28 (edited 12-10-2023).]

Even with the balance shaft GM put into the 3800s, idle vibration is still prevalent. It isn't really an issue above 900 rpm or so.

If you are doing a 3800 swap using a manual trans, the idle speed in those applications is going to be high enough the idle vibration isn't going to be an issue.

Auto trans applications utilizing stock stall speed converters are the ones that notice it the most. It can be mitigated by using rubber mounts (and in 87-earlier Fieros - keeping the rubber cradle bushings). If have an 88 Fiero and/or are using poly or solid mounts, it could be pretty bad. Even if you are using a stock stall speed torque converter in an auto trans application, the idle speed can be bumped up in the tune a little bit to help - but it will still be noticeable.

-Ryan

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More is more. Less is not enough.

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

I confirm.
The 3800 does vibrate at idle.
But above 1000rpm/1500rpm, the motor is smooth.
However, if you use poly engine mounts, there will be more noise and vibrations than with rubber.
However, a prepped 3800 will rip to shreds rubber mounts!
Regards,
Rafe

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"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM