sailtexas186548

iTrader: (2)

setup: turbo, 650rwhp, through a 6-speed, will most likely go built auto with a loose converter when the t56 takes a dump, all spohn rear suspension, chassis mount tq arm

I am having a hard time deciding if i should go with solid or poly motor mounts.

The solid mounts will give me more room in the engine bay to work with, allow me to hard mount the turbo and take the weight off the hotside. I'm ok with the extra drivetrain vibrations, but is there any advantage/disadvantage such as more wear on drivetrain components due to the lack of flex in the whole driveline? better reaction time at the track with solid vs poly?

I'm having a hard time making up my mind, so any input is appreciated. Also, brands to buy the mounts from? spohn, bmr, umi, moroso, any preferences for you guys?

i will be running a poly trans mount as well.

thanks!

- Alex

EDIT: i put this in this section because there seems to be lots of knowledge in here, and race cars (xpndabl3, Ha!) so I imagine lots of solid mount guys

xpndbl3

iTrader: (5)

with that kind of power I'd be looking into a motor plate/mid plate combo with poly trans mount. Otherwise you're beyond the limit of solid motor mounts IMO. You're going to get some bore distortion in the block tugging on those mounts compared to a motor plate.

sailtexas186548

iTrader: (2)

ok, so your saying both solid and poly, or just solid mounts are going to create too concentrated of a load on the block because of where they attach, so I will start getting into block/bore distortion? that does make sense, but how to so many boosted street car's get away with regular mount locations? are they just running on borrowed time?

brandoz28

iTrader: (1)

it's one of those things that some people never have problems, some kill them. putting a motor plate in the car is the best way to do it, especially if you're planning on stepping it up down the road

ZONES89RS

iTrader: (2)

If you are willing to give up some of the "street" portion of the rude, the solids are fine, it is a bit rougher ride, the engine tweeks the car a bit more and you feel more "shake" out of a cam and what not.

If you think you can handle the manual steering box in my car and not wreck it, i will let you drive my car with the solid mounts to get a feel of what it is like on motor alone with no power adder(no you cannot use the nitrous, LOL).

The manual steering box is not for the faint of heart, so it will probably not be that easy to pay attention to the feel of the car with having to pay attention to steering the car.

xpndbl3

iTrader: (5)

personally in all the cars I've had or combos, I could never tell a difference between poly or solid mounts in them. In fact in some I thought the solids had less vibration issues, but this isn't a caddy, this is a 650rwhp car you're talking about. And everyone who has solid mounts and is making 800 hp or so on motor has bore distortion probably, I had an engine that had ovaled on either side where the mount was located when it came time for a rebuild/refresh on a stock sbc 010 block. For your level, the motor plate and mid plate is the best suggestion and will free up a lot more room for your turbo buildup.

greezemonkey

iTrader: (14)

You guys that have never had one, you would not BELIEVE what a midplate can do for your car on the launch and driving out of it. Mine went from two fisted white knuckle to one pinky on the wheel. Two plates with a limiter is the way to go

1BADRZ28

iTrader: (2)

this

built91Z28

Do you have to be at your power level to notice a difference, or would a low 12 high 11 second car notice a difference? I have solid mounts now mounted to a Spohn tubular K-member and keep reading bad things about solid mounts on tubular crossmembers. Plus I like projects

83 Crossfire TA

iTrader: (2)

Same here, I've put solid mounts in a few cars and have never noticed them getting significantly more harsh. In some cars you'll notice a tighter front suspension since now the engine becomes a solid part of the front suspension

AlkyIROC

Front and mid plate in my car and with a lightweight powerglide, I don't even use a tranny crossmember any more.

For serious power, you should be considering at least a front plate instead of side motor mounts. It's much better than using the side mounts however you do lose some access in the front along the sides of the engine. The front plate however does offer places to mount other components. With the front plate, the engine becomes solid with the frame. I have my alternator spun around backwards with an adjustor mounted to the frame rail.

When using a front plate you will need to install limiters to keep the engine from moving forward and backwards. The movement isn't great but over time, it will crack the front plate. Because of this movement, a solid tranny mount isn't recomended as it may crack the tailshaft housing but few people have experianced this. This would happen only if the frame sees severe twisting.

Installing a mid plate offers more support instead of having all the engine/tranny weight supported by a front plate and tranny mount. I ran without a mid plate for quite a few years with no problems. It feels safer to have a mid plate in case you break the tranny bellhousing so the back of the engine won't fall onto the firewall or ground.

Using front and mid plates also allows you to position the engine/tranny to wherever you want. My engine sits lower and is moved back as far as my headers will allow.

When positioning the engine/tranny in the car with a front and mid plate, aim the tranny output shaft at the diff yoke. It makes setting up driveline angles mch easier.

greezemonkey

iTrader: (14)

Tough one, cant say I have seen many 12 sec or 11 sec door slammers with mid plates and if I did I guess Id question why a car with that kind of et has it or wonder whats this thing really do since its got a mid mount in it? Best why I can answer is this...

A good amount of nitrous off the line YES

Trans brake launch YES

Fast stick shift car YES

otherwise if it`s 11 or 12 with a std auto with a medium stall speed of say below 4500 I dont see how it would help but on the other hand it would`nt hurt for sure

chevyredneck8

iTrader: (4)

What is the midplate ur talking about greeze monkey?

AlkyIROC

It's a thin metal plate between the block and the transmission that holds up the back of the engine when using a front motor plate so all the weight doesn't sit on the transmission tailshaft. It's bolted to brackets welded to the frame rails. There's also a spacer that sits between the crank and flexplate to move the torque converter back the same distance.

With a front and rear plate on my engine and I only use a powerglide, I don't use a transmission mount at all. The tranny just bolts to the engine and hangs there.

Because front and rear plates will still flex, there are also limiters installed to keep the engine/tranny from moving forward and backward. Mine is mounted at the back of the tranny to the driveshaft loop crossmember.