BlackTop/SilverTop Hybrid

**DeftAnesthetik** · 10-02-2006, 11:28 AM

Hey all just wondering if anyone has any experience or knows of anyone who has put a B/T head on a S/T bottom end? I have little doubt that it can be done but was wondering about any gains in doing so? I am still debating what way to go for my conversion as i am thinking about future upgrades and i understand the B/T bottom end is not quite as strong as the S/T, but I would rather have a MAP engine than AFM. am i just being paranoid, i have read that the B/T "explode" with any kind of forced induction, is this just talk or has anyone seen/heard of this actually happening. I am not after the best BANG/BUCK nor am i after pure POWER, but i am only interested in the BEST way to build my 4A. I have read so much and keep searching the net all the time (I have been losing sleep over this upgrade, even though it is still in the planning stage) "IN USAGE" infomation on the 20valves is very limited. I know of the issues involved in installation, i know of the differences between the engines, any input from those with experience would be greatly appreciated.

**4agte** · 10-02-2006, 11:40 AM

build a 7age

**DeftAnesthetik** · 10-02-2006, 01:44 PM

thought about that one already, may attempt at some point in time but right now it is just too much displacement for me. I want to keep this build NA and from what i have read the 7a only truly shines with forced induction. Thanks though

**Starfire** · 10-02-2006, 01:49 PM

The main reason that the blacktop doesnt handle forced induction well is the increased compression. If you really want to go for forced induction I would suggest a blacktop head on a GZE bottome end.

Other than that I would get a 20v and drop a set of cams in it.

**2revup** · 10-02-2006, 02:42 PM

agreed best bang for buck + pure power will come out of 4agze engine, if you really want a 20v head, then go for it. on the 4agze block. also when you are referinf to afm and map. and you want pure power, you will always have map because at the stage you said you want power, this means new computer management system, your stock computer can be used as a placemat.

good luck

**DeftAnesthetik** · 10-02-2006, 03:09 PM

Originally Posted by Starfire

The main reason that the blacktop doesnt handle forced induction well is the increased compression. If you really want to go for forced induction I would suggest a blacktop head on a GZE bottome end.

Other than that I would get a 20v and drop a set of cams in it.

Am i right in thinking that i am getting the hi-comp from the blacktop head, or am i getting the increase from the block/pistons? also are you saying that the b/t block is the same as the s/t? i am still unclear on this one, i have only found one reference on the net that says the blacktop has a weaker block and once is not enough to convince me but it is enough to make me think twice.

i definately want the 20 valve but in the beginning i am going to go NA, i may however decide later i want to force some more air through so i want to be ready for that and not have to build a second engine.

i am thinking the same way as you, either way i go (black or silver) i will be getting some cams and doing port/polish/valves and exhaust.

**Starfire** · 10-02-2006, 03:39 PM

I am unsure of any differences in the bottom ends of the black and silver other than the black having higher compression pistons.

Where you have a problem is deciding if you want NA or boosted power. The path to one is not the path to another.

For NA you want high compression and lumpy cams. For boosted you really want a low compression and fairly mild cams (stock should be fine) along with plenty of boost. If you boost a high compresison engine with much more than a few psi it is likely to break. A low compression na engine is going to make fuck all power.

**myne** · 10-02-2006, 03:41 PM

IIRC the silvertop has the same rods as a gze. All you'd need then would be some GZE pistons for either 8.0:1 or 8.9:1

**2revup** · 10-02-2006, 04:26 PM

honestly if i were you and you have the thought of fored induction into your head i would stick with only a silvertop motor - complete block n head, i say this because parts are easier to get and the extra power will mostly come from the extra compression in the blacktop, and even then its minaml. and most of all its just a cheaper engine then the blacktop.
then if need be rebuild that when you want forced induction with the right gear pistons, Rods, fuel system, turbo manifold and all the other little extras.
better start saving your pennies.

**OSJ** · 11-02-2006, 06:11 AM

A Blacktop has 5hp more than a Silver,woopee!! The Silver top also reaches it's maximum torque lower in the rev range,better for drivability.

**AE101LEV** · 11-02-2006, 02:35 PM

get a gze and turbo it.. that way you have forgies at least, 20v heads on Gz's area wank factor just to say u have 5 valves per cyl, i was plannin on puting my BT head on my gze and putting a Garret T3 highflow on it, but the heads a pointless excersise, especially that the ports are smaller in the 20v than the gze if you get urself a good set of HKS cams i wouldnt worry about it.

**finney** · 11-02-2006, 05:13 PM

if you thinking of boosting then just go for the GZE, the extra money you pay for the engine will be worth it as to boost a 20v you will have to do a lot of work, whereas the gze is already half way there. i currently have a silvertop and it's great for daily driving and the occasional thrash through twisty roads. i have considered boosting it but its a very expensive excersize and i doubt i'll be doing it any time in the future.

If the only reason you're after the blacktop is for the Map remember that you can attain this on a silver with an aftermarket computer. If you are considering putting in some cams then you'll probably require one of these anyway. just do the maths on each one and see which one is going to be the best bang for buck option.

also out of curiosity what car will this be going in?