Modding a 7GM

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Modding a 7GM

Post by Jagman212000 on Wed May 27, 2015 9:13 am

I am wondering why I always see engine swaps as opposed to modded 7GM engines? Are the factory engines not receptive to upgrades? Also I have seen complete turbo 7M engines on eBay for under $1K. Would it be worth it to buy one, refresh it and drop it into my 92 Cressida? My car is non-turbo as I think all US Cressidas were. Any insight? I'm not looking for a race or drift car but a little more power would be nice.

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Re: Modding a 7GM

Post by Gordon Duax on Sat May 30, 2015 7:55 am

Because it's cheaper to buy a half worn out JZ or UZ than it is to rebuild a fully worn out 7M (or any engine for that matter).

And guess what, just about all the half worn out swaps I see, end up having the exact same problems, leading to yet another engine change.

Doesn't make any sense to me, but what ever.........

In the past few months, I've seen 1JZs, 2JZs, 1UZs have the same problems that the 7M has, and these were all by people who hate the 7M.
Things like rod & main bearing failure, ring lands blown out, endless oil leaks.

These are not skate boards, you just can't go down to the local store, buy a new set of trucks or wheels, and throw them on.

Too damn many people getting into Cressidas, or tuner cars in general, that have no idea what the #uck they are doing, couldn't keep a dead stock honda running if their life depended on it, and think they are going to throw together a performance car.
Not going to happen, never, nada......

I have been playing with 7Ms from before some of the latest wana-bees were born.
There is only a few things that the 7M is lacking in, and those have excellent cures for them.
Keep in mind, the 'M' engine dates back to 1965, and there has been a bunch of new things found to make them last longer.

The 7M suffers from too little gasket area around the bores, too small of an oil pump, and a head, that if it has been over heated, will allow the head fastener wasshers to sink deaper through repeated heat cycles.
And in the case of the Cressida, a poorly designed oil pan that allows the oil to slosh back away from the pump durring hard acceleration, or when in mid drift.
All have good fixes!

I had been turning mine to 8500, with ZERO problems.
The Malta dragster turns 10.500 throught the lights, so on this go around, my reve limit will be set at 95oo.

The oil pans can be modified, oil pumps can be driven faster, and ARP not only makes studs for the head, but also stepped washers that keep them from sinking deaper into the head durring heat cycles. (they make them for all the new US engines with aluminum heads, that have the same problem)

As someone once said on one of the Supra forums, 99% of the 7M problems are caused by the owners.........
My last failure was due to a fuel starvation problem, had nothing to do with it being a 7M. Either my original fuel pump went weak, or an original injector gave up the ghost, and I torched a piston at the Texas Mile.
Both were do to me not taking care of things that just don't last 25 years.......

There are several 700HP 7Ms in Supras, that have zero problems, and are daily driven.

Enough for the lecture, I'm going back to JZXP, where I can harass the 1JZ guys, every time they loose an engine, without worring about hurting someone's feelings Smile
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Gordon Duax

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