silvertop mods

[Boost_4_Life]

before anyone tells me to search... i did.... and i got fustrated with it...

plans are underway for next rally season, and we want to give the engine a birthday. its stock standard silvertop, standard ecu with only filter exhaust etc.

i have access to a very good machine shop/engine builder. what i need to know is where we can make good gains with this engine. the plans to do a complete freshen up, balanced bottom end etc. then obviously head work, mild porting/polishing etc. as far as cams/valve springs other things what will give good gains? i have no idea of a power figure in mind, i'm not expecting miracles. I need good midrange punch right through the rev range, i dont want a peaky motor. so in this regard i dont know whats available in the way of cams and bits n bobs?

appreciate your help, i've searched the net a bit but everything is blacktop this and mix/match of parts. i want to try and stick with what ive got mostly. obviously we will be doing the ecu, that is a given.

discuss.

[touge_ae101]

major gains can be made in the ecu. take a look at how much effort affroman has gone to with head work only to recieve minimal gains. a decent ecu and tune would set you up pretty nicely for a base i would think.

[Santa'sBoostinSleigh]

if the Aff actually pulled finger and got an aftermarket ecu/tuned to suit his mods, im sure that it would actually unlock/make use of the work he has done.
....but Paul is slack and will never get to that point

[Boost_4_Life]

the guys at work keep trying to convince me to use a honda ecu, they tune them extensively here. but i cant be bothered with all the dicking around with the dizzy signals to get it to work, a G1 v5 link would be fine...?? They keep trying to tell me the honda computer has a lot better resolution in the maps, which could be right, but would the old G1 be that bad???

[touge_ae101]

might not be too much dicking around going to hondas ecu as from seeing how other people have made decent gains from a conservative 20V setup such as fxgt_race, wasted spark looks like the way to go.

[Boost_4_Life]

the honda would be sequential no? and link wasted spark (unless i buy a flash new link) ...?

[soopachargen]

as long as you dont go for a sega master system type link (eg get a modern one) it should be better and easier than using a tuned honda computer

even if you do get an old link i believe that they can update the software on it so that you are at least running the best software for the old hardware

might be a good idea to give Lith a bit of a tap on the shoulder, see what he thinks??

[RedMist]

the honda would be sequential no? and link wasted spark (unless i buy a flash new link) ...?

An engine is the sum of it's parts.... and ..... the tune.
Wasted spark isn't as much of a hinderance as you think. I ran 187whp on my 16 valve running a Link LEM V5.

Silvertop. Airbox, trumpets, exhaust, cams, ECU, CR, VVT trigger

The heads are pretty good, however you can remove the casting marks and redirect the choke to promote better swirl on the outer two intake ports. Piston, rods, bottom end are all good. The top end is also reasonable. If you have the room, put an adaptor between the heads and TB's to promote a straight intake path. There is a huge pressure spike just post the manifold face. Good gains were had on the flow bench by mocking up an adaptor. We never implemented it (I found a good 16 valve). This will probably put your TB's through your bonnet.

[Boost_4_Life]

good info guys thanks for this.

what signals come in from the silvertop dizzy anyway. the notes i have show three signals, G1 and G2 and RPM. what are G1 and G2 exactly?

[Boost_4_Life]

So, Ive got a good ecu lined up. the plan is to first get this in, at the same time converting to map sensor and getting rid of the afm. Once ive got a base tune and it runs then we will do the engine work early next year.

the g4 has internal map sensor so i need to pick up a vacuum feed for it, where is a good place to do this on the silvertop???

[whynot]

If you look closely under the throttle bodies you will see a small vac line which is joined into each throttle. I am pretty sure it then joins into the vaccum manifold on the right hand side of the motor next to where the ICV is plumbed into. thats where i got my vac signal from.

[Boost_4_Life]

cool ta ill take a look over the weekend.

[whynot]

you will know if you find the wrong one as the vac signal will be bouncing all over the place

[sergei]

If you look closely under the throttle bodies you will see a small vac line which is joined into each throttle. I am pretty sure it then joins into the vaccum manifold on the right hand side of the motor next to where the ICV is plumbed into. thats where i got my vac signal from.

The small manifold where the PCV valve is feeding off is the right place. It will have a round steel plug on the one end and it will have whole bunch of vacuum feeds coming off it. You could either tap a new feed or use one, if for example Purge solenoid is not used.