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Author: Subject: Rebuild or put it together and hope for the best

posted on 6/3/19 at 01:49 PM Reply With Quote
Rebuild or put it together and hope for the best

Hi all, been a long time since I was last on here. I was doing an engine swap on a Sylva striker a few years back from xflow to duratec. Unfortunately I got as far as having everything fitted together and plumbed, but never got as far as installing the omex and firing the engine. Selling our house and garage where my car was forced selling it in its state at the time. Fast forward 6 months and I bought myself a ready built and running rotrex 4age powered raw striker and have been enjoying it for weekend and fast road blasts for the last 18 months with nothing other than servicing and tinkering to keep it running sweet. Itís a fairly recently refreshed 4age 20v silvertop running at a very moderate boost level and producing 210bhp and 150lbft. While itís more power than Iíll ever need on the road, on a track it could do with more. Most things on the car are set up ready for more power, heavy duty type 9, clutch and diff and bigger front brakes. All Iíll need is bigger injectors, different Rotrex pulley and a mapping session for over 250bhp 😊. The 20v 4age is a high compression engine however and probably wonít take much more boost reliably. With that in mind, Iíve sourced a supposed 70,000km 4agze engine which uses the same block as the 4age and will bolt straight up to the 20v head. The 4agze being supercharged is slightly lower compression and has semi forged pistons and is know to easily take 300hp out of the box.
Now at last my question. The engine has been lying around in the persons garage I bought it from for quite some time. I did a quick leakdown test on it and the results were around 20% on a couple of cylinders, however it sounded like that was all escaping from the inlet valves which had the odd rust spot on them. Iím about to pull the cylinder head and do a very basic check on the state of the bores. If these look and measure ok, whatís the opinion on just bolting the silvertop cylinder head up and hoping for the best? Iím trying to avoid a full bottom end rebuild, but if people think itíd be advisable im capable enough of changing out the main and big end bearings. Obviously if the bores are damaged or out of shape Iíll be looking at a hone or re bore and new rings at which point Iíd get the bottom end fully rebuilt anyway

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Angel Acevedo

posted on 6/3/19 at 02:01 PM Reply With Quote
Even if journals dont show wear signs, Iīd check them, and once you are there, fit new bearings.
If it happens that there are visible uneven wear, yo have to do it anyway if you will be running high power...

Beware of what you wish.. for it may come true....

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ian locostzx9rc2

posted on 6/3/19 at 04:06 PM Reply With Quote
I canít see the point in not checking the bottom end you will have the engine in bits anyway
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posted on 6/3/19 at 04:27 PM Reply With Quote
Thanks for the comments. Iíve got a set of calipers so will take your advice and drop the sump and measure and check the condition of the journals before I go any further. all being well Iíll replace the bearings before proceeding.
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posted on 6/3/19 at 04:32 PM Reply With Quote
As above
I'd drop the sump and check the big end and main bearings
Having a look inside the sump will give you an idea of what sort of life its had

It'd be a shame to only go so far with the checks and then it turns around and bites you when your on a track day ?

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