20V BT VVT with aftermarket cams

[86JAP]

Car - 86

motor - Black Top 20 Valve

use - daily bit of drift

problem - not so much a problem i would like to know what is involved in removing the vvt set up to run A/M cam gears? I know with the Toda gears u can keep it but just researching all the options.

Thanks in advance guys.

Sam.
_________________

[Sam-Q]

unplug VVT solenoid, put gear on, sell VVT gear

what ECU are you running?

[Jonny Rochester]

You can simply unplug the solenoid. I have removed the solenoid myself, and I make up a little alloy bung to replace it. I can make one for you too if you like. Im just about to make a handfull of them.

[86JAP]

thank guys, its actually a mates car im referring to but always wondered myself and will need to know when i build my next 86.. anyway at the moment its running 292 degree toda cams with vvt still in operation and running a Haltech E8.

[Sam-Q]

with what lift cams?

[86JAP]

cams have 8.1mm lift

[Sam-Q]

yeah just as I figured, it's hard to get information on this subjuct but it seems that using higher than stock lift means you can't have more than 270 degrees duration, but I the limit for longer duration is probably around 8.5mm

[86JAP]

Thanks Johnny and Sam dunno what my mate is gonna do but ive pretty much decided on removing it, simply because the next motor i build will have fairly high compression and i dont want VVT to kick in at the wrong time and bend some valves lol..

[Sam-Q]

what spec cams and what C/R are you thinking of going for?

[4000GT]

This thread is all wrong... you can get high lift high duration cams on the BT 20v, I have 288 with 10.0mm lift and 12.5:1 comp. Not running the VVTi will totally destroy the mid range power, we tested this on the dyno and dropped 20WHP through much of the rev range on a stock motor. I dont understand the comment about hitting valves with VVTi "kicking in" at the wrong time and bending valves, we played around with VVTi engagement points from 1,200rpm and up and guess what, the factory has it in the optimal position, much like the intake setup... if you do run adjustable cam gears, expect to spend hours on the dyno dialing them both in for where ever you want to make peak power.

[86JAP]

Sam-Q- not sure yet still doing research but i would like to do a 7A20V, got a bit to learn first though.

4000GT- never mind that comment before upon actually thinking about what goes on with the VVT i am mistaken..

[Sam-Q]

86jap: can I suggest if your going for a 7A bottom to run silvertop pistons?

4000GT: you see this is why I hate this subject and why I have no hard facts stated on my website about this. Because I couldn't get any solid answers I just gave answers for what actually is proven to work.

[4000GT]

Yeah I can see why its frustrating. And generally people mucking around with these motors dont spend a lot of time on the dyno testing different length intakes, or intake systems and different diameter and length primaries on the exhaust etc. It just costs a massive amount of money and potentially adds no power. Im luck in that my flatmate owns a dyno shop and we get a chance to play around a bit more than usual. In essence, the stock intake is best (tested on stock and modofied cam motors). Even the stock exhaust manifold is excellent, even though it looks terrible.

[86JAP]

Sam u can suggest what ever the hell u like, like i said im still learning about this conversion and weighing up my options.. If i do it i would like to have around the 200hp mark and will look into all the options to get this, i think it is quite possible but its all gonna come down to how much money i have to spend on it. Why do you suggest ST over BT?

4000GT: When you say stock exhaust manifold are you refering to the standard FWD manifold? I have a BT in my AE92 at the moment running only a Haltech e11v2, trumpets, and a 2-1/4 inch exhaust from the stock headers, it makes 140hp at the front wheels which i though was pretty good for what is done to it.

[4000GT]

To get around 200HP, youll need a properly designed intake with trumpets and a long intake pipe off the manifold to a cold air box, the biggest cams you can physically fit and the parts that go along with it like uprated valve springs and some ARP rod bolts. At the same time get them to reseat the valves and wind in a decent amount of comp, Im running 12.5:1 but on pump gas, you can run more depending on the fuel you plan on using the BT chamber design seems quite capable of taking some comp even from factory. Then spend some time on getting a decent 4 into 1 exhaust manifold, not sure on the primary lengths as it will vary on the cam choice etc.

I was referring to the stock 4age RWD exhaust manifold. Oddly enough on a 20v in a DX track car, a mate designed long primary runners all equal length and looked a million bucks and in testing on the dyno, the stock RWD manifold made more power everywhere. My BT in my old AE101 made 132WHP on a pretty much stock setup, unopened engine, just an ECU.

I am hoping for 150-160 on the worked motor I have sitting in the garage now. Will see.

[4000GT]

Oh and probably $5-7000 depending on specs etc.

[86JAP]

Thanks man, helps heaps, is it a 1600 your building? specs or is it a secret? Im not decided on anything at the moment my goal is to have a motor with a decent amount of power (doesn't have to be 200) wheather it be 1600 16V, 1600 20V or 1800 16/20V and i want it to have that lovely "lumpy" idle lol.

[Sam-Q]

I suggested silvertop pistons with the blacktop heads because it offsets the compression ratio raise of the 7A bottom end. Depends how high you want to go, keep in mind I hear multiple reports that going to the 7A bottom doesn't lift power it only shifts the curve 1000rpm lower, true or not I dont know. Well either way with that power goal you need an adjustable VVT cancelling gear, simple as that. Or you casn mod the existing one but thats a waste

4000GT: yes it's really frustrating, I want to know if I can run VVT with 9mm of lift and 280 degrees of duration measured at no lift without any issues. I don't have the money to find out.

[4000GT]

Well, Ill be running 288 degrees and 10mm of lift. Ill take video footage on the dyno in 2-3 months when its ready to go on.

[Sam-Q]

I look forward to it

[86JAP]

Thanks fellas very helpful, gotta get my shit together so i can start this.

Looking forward to that update too!

[slider4life]

hi guys thanks for all the replys im the one that owns the ae86 that sam is askin about mods to car are haltec e8, trumpets, and the guy i bought it off said they are toda 292 with 8.5 lift i have found that toda dont make a cam that specs. its more like 272 with 8.5mm lift. so what you guys are saying is that it not worth the money im going to spend to put a/m cam gears on and that you would just keep your vvt ???? reason i was lookin into this is beacuse when i rev the car up to about 7500 it feels like it not making any more power but the guy i got it off sayin it makes power to 8500 im not sure though.

[Sam-Q]

make sure the VVT is actually being activated and turned off at the right revs or else the power will drop off real quick.

[4000GT]

I had those Toda cams oddly enough, and ended up selling them to a mate of mine. He had them in his modified blacktop and the cams actually wore down over time. Presumably the oil used, and the lobes were literally grinding down. This is in a well spec'd track car. he made circa 150WHP with those and other mods. The cams dont make power to 8500 rpm, and saying that is silly really as it depends on so many other factors like intake and exhaust resonance etc. If you drop the VVT, expect to lose around 20WHP again over the low and mid range and gain nothing up top.

[slider4life]

4000gt thanks mate that answers that question be happy with what you have lol ill be looking at the exhaust next as its 2and a half all the way threw except when it goes over diff it restricted as all shit.

[Sam-Q]

over diffs can be great but it needs to be right, maybe you should look at that first?

[slider4life]

so would you recommend over diff or under diff what the guy has done is yuk and the exhaust isnt mendal bent so at each 90 deg it closes right up

[Sam-Q]

I would always go over because I like to keep my exhaust well off the ground and looking legal. Many people on here will go for under diff, I am unsure why exactly though, it's not like theres a power gain to be had if they are both done right

[4000GT]

Are you not able to side exit? We can here as long as it exists after the door. This is what I am doing. Also, with the bends at the end of the exhaust, the velocity of the gasses is so slow by then (compared to out of the head), I really question how much the reduced CFM really matters there. I guess this raises the whole issue of NA tuning and back pressure...

[Sam-Q]

I have done my own backpressure testing and I personally have proven that any backpressure is bad. As far as I know the further up the exhaust you get the less it matters. I am making good power with my over diff and would be betting on there being no power gain by an under diff.

I am going to change the topic of this thread

[4000GT]

Well, yes any back pressure is bad (to a point), you dont want in worse case scenarios to have reversed flow. But to have an exhaust size that doesnt create any back pressure is one thats too big and adversely effects gas velocity. If you dont have velocity in the high speed pulse then you dont scavenge low pressure gasses. Ergo, a 3" exhaust on a 4AGE NA for example will produce less power than one with a 2.5 inch, as the gas velocity in the 2.5 inch is much greater, allowing better scavenging, and higher gas velocity. Yes the 3" has less back pressure, but ultimately worse for power. Its really about balancing back pressure and velocity...

[Grant #2]

I've been asking this question over the net....

4000GT, Kelford cams is telling me their B spec cam (270 in, 8.72mm net valve lift) won't work with VVT on a blacktop.

You make it sound as if you can actually get away with much more duration than that. Any input on the matter?

I pretty much only have enough time and budget to buy cams once, and I want to get as aggressive as I can while keeping VVT.

Thanks!

[slider4life]

well mate im running the toda 272 with 8.5 mm lift and to me it sounds tuff as for a 1.6 has an eratic idle between 1000 and 850 to 900

[4000GT]

I've been asking this question over the net....

4000GT, Kelford cams is telling me their B spec cam (270 in, 8.72mm net valve lift) won't work with VVT on a blacktop.

You make it sound as if you can actually get away with much more duration than that. Any input on the matter?

I pretty much only have enough time and budget to buy cams once, and I want to get as aggressive as I can while keeping VVT.

Thanks!

Odd, I brought my 10mm lift 288 cams off the owner of Kelford last year... didnt seem to worry him then! My friend who I sold the Toda cams to is running VVT on his track car, no issues. What was their reasoning when you talked to them?

[Sam-Q]

4000GT: well said on the backpressure, now when you bought the cams previously did you mention it was for a silvertop? Do you think there is any truth in the valve hitting pistons with VVT subject?

[slider4life]

here the link for specs on the toda cams if this helps

http://www.todaracing.com/en/product/cam/4ag5v-1.html

[Grant #2]

Yeah I was just looking on that.

4000GT, I just read what you posted in my other thread. I'm not trying to get tame cams, I would like as aggressive of cams as I can. My only requirement really is that the cams are 75% the cost of new Todas, and that VVT is retained. I do have a stand alone, and I'll be doing my own tuning, so I only need to rent the dyno.

That being said, the US sales rep is the one that told me I can't use the Rally grind. I think the Rally grind would be ideal though, if it works for VVT. 270 in, 280 ex., around 8.7mm of lift. If I can get even more lift, the better, but I can't afford to buy a new blacktop engine if I drop a valve. The intake and exhaust gaskets are metal, and easily re-usable, so I don't see gaskets being a major expense.

I suppose I should call Kelford direct in NZ and see what they have to say on the matter...at the moment they are my number 1 choice - good specs, decent reputation, and really good price!

[Grant #2]

One other thing, I have a blacktop....maybe it is possible the blacktop has much less room for valve lift on the pistons? The chamber has more CC, and the C/R is higher, so I guess that means the pistons must be "taller"?

[Sam-Q]

the head wouldn't need to come off for a cam change? and I have reused the seals for the cam cover lots of times without any issue

[4000GT]

Well, I have never heard of the issue of running high lift cams and VVT, and really I cant see how removing VVT would help if impact was inevitable. Its simply putting the cam through a motion which at some point the stroke would cycle through if the VVT was removed and an adjustable cam gear was used. RPM doesnt come into it and the cycle is the same, just quicker. It would be odd to expect that after a cam install that you use an adjustable cam gear and hope that the setting you use is one where the VVT range wasnt else bent valve.

I went for Kelfords for the same reasons, cheap, good range of specs, plus I live two blocks from their shop :)

[Frak]

I've been asking this question over the net....

Kelford cams is telling me their B spec cam (270 in, 8.72mm net valve lift) won't work with VVT on a blacktop.

You make it sound as if you can actually get away with much more duration than that. Any input on the matter?

I pretty much only have enough time and budget to buy cams once, and I want to get as aggressive as I can while keeping VVT.

Thanks!

Grant, tomorrow when I get back to work I'll print off some dyno runs I did of a ST running these cams, the ST had a late haltec ecu, headers etc, we ran the engine up with std cams, then fitted the Kelford on the intake only, tuned engine etc, then fitted the Kelford exhaust cam and re tuned.

The Kelfords used were the 194-B's intake 270deg dur, exhaust 280deg dur. VVT was retained, vernier exhaust cam sprocket.

[Grant #2]

Thanks a millions dude!

=)

[Grant #2]

Man, I hope a blacktop can also clear that cam. So far, this has been my number 1 pick out of the few cams I've seen available. If it doesn't clear...I dunno, relieve the pistons a bit if possible, switch to ST VVT gear, and 2 headgaskets maybe? =(

[Sam-Q]

Well, I have never heard of the issue of running high lift cams and VVT, and really I cant see how removing VVT would help if impact was inevitable. Its simply putting the cam through a motion which at some point the stroke would cycle through if the VVT was removed and an adjustable cam gear was used. RPM doesnt come into it and the cycle is the same, just quicker. It would be odd to expect that after a cam install that you use an adjustable cam gear and hope that the setting you use is one where the VVT range wasnt else bent valve.

I went for Kelfords for the same reasons, cheap, good range of specs, plus I live two blocks from their shop :)

I think it's to do with the timing of when the valve opens instead of how far it opens

[DX20VT]

I think it's to do with the timing of when the valve opens instead of how far it opens

Possibly, the standard specs for the ST and BT are different in timing by 5 degree's,
but the difference is in the cams themselves, the camgears are identical and interchangable in timing,
they only differ in cam belt width.

[Grant #2]

If that is true, my dad was suggesting I drill another hole some where on the pulley and align it with the teeth for the belt in a way that I reduce the advance by whatever it takes to not risk interfering. I would have to remark the TDC marks too.

[Grant #2]

Bump for Frak =)

[Frak]

Grant, PM me your address and I'll mail the dyno runs to you, I will NOT be posting them up, if you want to once you get them, that's up to you. I'm on the verge of pulling the pin on this site, I've had enough of retards, I guess there was a reason a number of people were previously banned!

[DX20VT]

If that is true, my dad was suggesting I drill another hole some where on the pulley and align it with the teeth for the belt in a way that I reduce the advance by whatever it takes to not risk interfering. I would have to remark the TDC marks too.

I did quite a bit of research on it as I wanted to know why I was told I could not run my TODA ST adjustable cam wheels on my blacktop.
I was actually looking to see how far off centre I had to put them if I was to use them on the wrong setup,
so I have a couple of ST and BT engines, and I spent a couple of weeks in tha garage at nights with a dial gauge and degree wheel and degree's out all the different cams I had with each of the pulleys,
and found that the difference in timing is not in the wheels, but the cams.

The question now is why do the ST and the BT run the same cam timing, profile and lift,
but at different timings by 5 deg?

[Grant #2]

NICE info man, you saved me a lot of time right there.

I has ASSUMED that the difference was the VVT pulley. Well here's a question, don't the two VVT pulleys have different part numbers? What is the difference there then?

[Grant #2]

PS, if only the cams are different....why couldn't you use the ST adjustable wheel on the BT then, just off center?

BT supposedly is slightly more lift. But often companies will use the same cam and just change the timing to get better emissions, or shift the powerband, etc. It was very common with Fiats and Alfas in the mid 70's to early 80's.

[DX20VT]

PS, if only the cams are different....why couldn't you use the ST adjustable wheel on the BT then, just off center?


Exactly, There are different part numbers for TODA ST and BT adjustable cam wheels,
which made me think they were not interchangable, but they seem to be so that's what I will do.

[Sam-Q]

I beleive the pin diameters are different

[Sam-Q]

hey Frak I cant send you a pm for some reason, anyway I would like to see those as well as your original ones you posted. My email is sam @ s-86.com (remove spacers)

[Grant #2]

I did try to send a PM the day you posted. If you didn't get it, my email is dorifto at sbcglobal . net. Thanks a lot!