Tomei Poncams 258 . . . anyone got em?

[GLoBaLReBeL420]

Anyone switched over to the new 258's that Tomei is putting out? I recently jumped over to them and am noticing some pretty crazy vacuum drop at idle. With the stock cam-shafts I was pulling -20 to -21(at sea level in Cali) no problem. I just switched over to the 258's and I'm barely pulling -14 now at idle. I had to bump my idle up to 950 rpms just to keep her stable.

I haven't had a chance to dyno her yet, but I feel like she pulls WAY harder up top 5K+ but I lost a ton of torque down low (3500-5K). Just seeing if anyone else noticed the same issue?

SR20DET S13 Blacktop
Tomei 740cc injectors
GT2871R (.64AR)
SS headers
Z32 MAF
ACV-R Boost Controller @ 1.2 Bar
Walbro 255 FP
Fuel at 43 psi no vac

Any input is greatly appreciated..

Already tuned with NisTUNE

[geiesrp]

that doesen't sound what tomei promised about 'stable idle' bro :(


well, I bought them too, they ll arive in the next few days. ill send you an update as soon as they are under the hood. As for me, i'll put them in with new lifters, rockers, oil spray bars, some Kind of mini revision. I know two other guys (one from Germany, the other from Austria) bought them too.

[240boosted]

yes my vacuum did drop at idle also not too much but i did drop

[GLoBaLReBeL420]

that doesen't sound what tomei promised about 'stable idle' bro :(


well, I bought them too, they ll arive in the next few days. ill send you an update as soon as they are under the hood. As for me, i'll put them in with new lifters, rockers, oil spray bars, some Kind of mini revision. I know two other guys (one from Germany, the other from Austria) bought them too.

Did you ever get those cams in? Trying to see if anyone else is noticing the vacuum drop at idle? Under deceleration I pull a good -19 to -22 ng and that's what I was pulling at idle (at sea level) before I had switched out the cams.

Also, is anyone else switching their valves and springs with these babies? I only run my 93 SR BlackTop to about 7200 rpms, but I can tell these cams would really shine with a much higher rev range. My turbo woulnd't be so happy, but the car would certainly enjoy it haha.

[Kingtal0n]

The small tomei cam (256) with low lift is ideal for daily drivers

The vacuum at idle should be in the 18" range

If you are only getting 14" they may need to be degree'd
Or they are off a tooth

I believe the 264's with a healthy lope pull around 12-14"

If you upgrade springs, use the same manufacturer (tomei cam = tomei springs) as a general rule for sr20 engines.

[240boosted]

well now i switched to haltech with greddy intake manifold built up engine a bit more but I want to say king is right 18 ish was mine next week i tell you what mine is

[Xaser]

Ups, sorry i wrote in spanish, i think cali as colombian city, no california.

Yes is normal, becasue the cam is less efficient at low rpm, but better efficient at high rpm.
I have the 270's and i have to tune the After enrichment to let stable, a 1100/1050 rpm, with big turbo, ported, big throttle etc etc. At 850 can idle, but is rough and with Air conditioned ON, try to stop.

PS: i delete the iacv because he try to stabilize and make "less stable " the idle.

[pacotaco345]

Did you ever get those cams in? Trying to see if anyone else is noticing the vacuum drop at idle? Under deceleration I pull a good -19 to -22 ng and that's what I was pulling at idle (at sea level) before I had switched out the cams.

Also, is anyone else switching their valves and springs with these babies? I only run my 93 SR BlackTop to about 7200 rpms, but I can tell these cams would really shine with a much higher rev range. My turbo woulnd't be so happy, but the car would certainly enjoy it haha.

I ran 256 poncams in my car for years, only recently when the motor ingested a throttle screw (which held an intake valve open, threw a rocker and trashed the intake cam) did I spring for new cams and valvesprings (JWT C2 cams and their recommended springs).

From my experience stock valvesprings with 256 poncams are good for at least 7600 rpm, thats what my rev limiter was at. Those cams were designed to work with stock valve springs so throwing stiffer springs and titanium retainers under them often does more harm than good. I've seen people with stock cams and BC springs/retainers throw rocker arms at like 7200 rpm while I've never had an issue.

[LoSt180]

Stock headgasket blew, these are on my list of "while you're in there" mods.

S15 SR20DET btw

[GLoBaLReBeL420]

Has no-obne else switched to these yet? I called Tomei and they told me that I shouldn't have that large of a drop in vacuum and my midrange should stay what it was, but it sure doesn't feel that way!

[GLoBaLReBeL420]

The small tomei cam (256) with low lift is ideal for daily drivers

The vacuum at idle should be in the 18" range

If you are only getting 14" they may need to be degree'd
Or they are off a tooth

I believe the 264's with a healthy lope pull around 12-14"

If you upgrade springs, use the same manufacturer (tomei cam = tomei springs) as a general rule for sr20 engines.

Thank you for your help!!

I've checked the timing MULTIPLE times and rechecked the teeth count on the cam gears and everything looks good to me.

Are there any quick tests or ANY tests i can do to validate my timing is correct other than my timing gun and counting the number of links on the chain between the two points on the cam-shafts?

I have it tuned to run at around 17 PSI and it holds great and doesn't break up or lose spark. Also running at around 11.8 - 12.4 AFR under WOT runs.

[LoSt180]

I got mine installed, and honestly the vacuum at idle doesn't appear to have changed at all. I just have the stock S14 DIN gauge though, so the exact numbers are hard to translate (it's range is -/+ 700 mmHg). At idle, the vacuum is down to almost -700, lets call it -675mmHg. Which is unchanged from my stock cams. This is in an S14/15 SR if that makes a difference.

As far as validating mechanical timing, the best option is using the colored links on the chain during install. That way you don't really have to count links, line up the marked links with the timing dots on the cams and that's it. You can see the yellow chain on the crank sprocket by removing the lower oil pan and looking up with a flashlight. That's how I set mine recently since I was replacing the head gasket with the engine still in the car.

I think setting TDC and counting links on the chain is the only "quick" option you have.

I'm having other issues now, so haven't had a good chance a driving impressions. Only thing I can suggest otherwise for your issue is to double check all your vacuum lines, including brake booster, and verify you didn't damage or get anything caught in the manifold gaskets that might cause a vacuum leak.

[GLoBaLReBeL420]

I got mine installed, and honestly the vacuum at idle doesn't appear to have changed at all. I just have the stock S14 DIN gauge though, so the exact numbers are hard to translate (it's range is -/+ 700 mmHg). At idle, the vacuum is down to almost -700, lets call it -675mmHg. Which is unchanged from my stock cams. This is in an S14/15 SR if that makes a difference.

As far as validating mechanical timing, the best option is using the colored links on the chain during install. That way you don't really have to count links, line up the marked links with the timing dots on the cams and that's it. You can see the yellow chain on the crank sprocket by removing the lower oil pan and looking up with a flashlight. That's how I set mine recently since I was replacing the head gasket with the engine still in the car.

I think setting TDC and counting links on the chain is the only "quick" option you have.

I'm having other issues now, so haven't had a good chance a driving impressions. Only thing I can suggest otherwise for your issue is to double check all your vacuum lines, including brake booster, and verify you didn't damage or get anything caught in the manifold gaskets that might cause a vacuum leak.

I checked my timing by doing the exact thing you mentioned (except I did it from above since I'm keeping my head on the engine and just looking from the top of the cam gears). I still beleive there's something else wrong. The car moves, and moves FAST but that vacuum issue is a real problem over the long run.

I'll just tear the valve cover off and see what I can check out again. UUGGHH!!

Note: I just did the conversions and -675 mmhg is like -26 in. Hg so that a crazy strong vacuum if that's what you're getting. A stock well built SR20DET should see almost exactly -20 in. Hg at idle.

[geiesrp]

I got mine installed, and honestly the vacuum at idle doesn't appear to have changed at all. I just have the stock S14 DIN gauge though, so the exact numbers are hard to translate (it's range is -/+ 700 mmHg). At idle, the vacuum is down to almost -700, lets call it .



I never saw such a strong vaccum on any SR. Is your stock ventilation hose (the hose beween valve cover MAF) still installed?


-700 = -0.93 bar

Anyone switched over to the new 258's that Tomei is putting out? I recently jumped over to them and am noticing some pretty crazy vacuum drop at idle. With the stock cam-shafts I was pulling -20 to -21(at sea level in Cali) no problem. I just switched over to the 258's and I'm barely pulling -14 now at idle. I had to bump my idle up to 950 rpms just to keep her stable.










I live in Switzerland, around 500m above sea level. With the stock cams and the tomei 256 aswell, I always had around -0.6 vacuum @ 850rpm.


With the 258 poncam it is way down to -5.2 at idle. However idle is fine. Timing is set to -15, no leaks.


@2000 rpm I'd -7.0bar with 256poncam. with 258poncam it is now -6.8bar @2000rpm.


I do not believe in a timing issue or leak. As for now I think going back to the 256poncam, since with the 258 change I have also changed the turbo from hks gtss to GTX2860gen II, which means i'll be unable to judge the cause of the loss in low or midrange.

[LoSt180]

I never saw such a strong vaccum on any SR. Is your stock ventilation hose (the hose beween valve cover MAF) still installed?


-700 = -0.93 bar

All stock vacuum hoses are still in place, even that little charcoal canister next to the radiator.

[GLoBaLReBeL420]

[/B]
I live in Switzerland, around 500m above sea level. With the stock cams and the tomei 256 aswell, I always had around -0.6 vacuum @ 850rpm.


With the 258 poncam it is way down to -5.2 at idle. However idle is fine. Timing is set to -15, no leaks.


@2000 rpm I'd -7.0bar with 256poncam. with 258poncam it is now -6.8bar @2000rpm.


I do not believe in a timing issue or leak. As for now I think going back to the 256poncam, since with the 258 change I have also changed the turbo from hks gtss to GTX2860gen II, which means i'll be unable to judge the cause of the loss in low or midrange.

I'm having as hell of a time converting values to get a feel for what everyone else is seeing vacuum wise for their cars.

-5.2 BAR is -153 Inches Mercury (which is CRAZY VACUUM compared to my -20 inches mercury)

I'm happy that I'm not the only one seeing the vacuum drop after the cam-shaft install. I'm just amazed that Tomei didn't say anything about where the car would idle at and the change in vacuum!!

[Kingtal0n]

25x is very small and should be 16-18" Hg idle 800~rpm

To verify what cam is, and how it is installed,
buy a CAMSHAFT DEGREE WHEEL KIT

and degree the cams in

[geiesrp]

I'm having as hell of a time converting values to get a feel for what everyone else is seeing vacuum wise for their cars.

-5.2 BAR is -153 Inches Mercury (which is CRAZY VACUUM compared to my -20 inches mercury)

I'm happy that I'm not the only one seeing the vacuum drop after the cam-shaft install. I'm just amazed that Tomei didn't say anything about where the car would idle at and the change in vacuum!!

Sorry, of coz i meant -0.52 bar, thats how much mercury?

as for units, me too. As far as I know you have normally -19 - -21 what? PSI? I found a pressure converter somewhere and the only value that fits was foot of something. Please let us tell the correct units, there are several people around the globe in this thread involved.


Just for clarification:
I'd -0.62 bar with stock cams AND WITH Tomei 256 cams.


Now with the 258 cams I have barely -0.54bar at idle. I might have an explanation for that behaviour. Maybe Tomei improved the cams for VVT, i.e when the engine runs VVT in 'sharp' mode. That would explain the massive power drop below 5000.


And if this is the case, I'll kick out the 258 right now. I actually bought them to improve lower and midrange, i don't drive the car in every gear to redline.

[Kingtal0n]

For S14 motors: Are you sure VVT is turning 'on' do you hear the solenoid click when you touch the throttle (move the throttle blade by hand from the engine bay). Also you can try disconnecting the VVT solenoid and see if the engine behaves better.

I Once had a set of 272HKS cams and the engine would run much better with VVT turned OFF all the time. I put a switch on it though because if you leave it off indefinitely it eventually drains of oil and sounds like a rod knock. So it was necessary to run the vvt once in a while.

[GLoBaLReBeL420]

For S14 motors: Are you sure VVT is turning 'on' do you hear the solenoid click when you touch the throttle (move the throttle blade by hand from the engine bay). Also you can try disconnecting the VVT solenoid and see if the engine behaves better.

I Once had a set of 272HKS cams and the engine would run much better with VVT turned OFF all the time. I put a switch on it though because if you leave it off indefinitely it eventually drains of oil and sounds like a rod knock. So it was necessary to run the vvt once in a while.

My engine is a 1993 SR20DET Blacktop, no VVT.

[GLoBaLReBeL420]

Sorry, of coz i meant -0.52 bar, thats how much mercury?

as for units, me too. As far as I know you have normally -19 - -21 what? PSI? I found a pressure converter somewhere and the only value that fits was foot of something. Please let us tell the correct units, there are several people around the globe in this thread involved.


Just for clarification:
I'd -0.62 bar with stock cams AND WITH Tomei 256 cams.


Now with the 258 cams I have barely -0.54bar at idle. I might have an explanation for that behaviour. Maybe Tomei improved the cams for VVT, i.e when the engine runs VVT in 'sharp' mode. That would explain the massive power drop below 5000.


And if this is the case, I'll kick out the 258 right now. I actually bought them to improve lower and midrange, i don't drive the car in every gear to redline.



So, -0.52 bar literally falls right where I am at with mine . .

-0.52 BAR = -15.35 In. Hg

My car reads at around -14 In. Hg after the 258 swap

Your stock cam and 256's read at -0.62 BAR (-18.3 In. Hg)

-18 to -21 In Hg is the normal for SR20DETs with stock cam shafts at sea level.

So, your drop was about 3 In. Hg and mine was more like 6 In. Hg, so a little worse.

Still think something is wrong with my setup even though the car runs great and everything. Its just driving me mad! :-(

[GLoBaLReBeL420]

I really want to get the car dynoed but I just haven't had a chance to take it to a dyno yet. I no longer have the stock cam-shafts so no matter what I'm sticking with the 258's, I would just like my car to be working as good as it can be.

[geiesrp]

guess what i’m doing right now. cover is already off, will double triple check timing, if right, 256 comes back in.

btw: car won’t start if a tooth is off

[geiesrp]

news.

double checked timing yesterday, pressured up the whole system, no leaks at all. only issue i found the vacuum is highly timing dependent, seems normal for these cams.

endgame: i have my old tomei 256 in and the vacuum ist now as before. reason for that i never felt happy with them, i wish tomei would provide a diagram to see what and where in rpm band are improvements done


@g revel: any news from your side? did u check the whole system for leaks?

[GLoBaLReBeL420]

I will be tearing off the cover and checking timing and everything to be sure but if the SR won't even start with a tooth off, then I know my timing is dead on. Did the timing gun 3 times after triple checking the number of links between the two markers on the intake and exhaust gears.

I really feel like these cams should have come with a warning about the loss of mid-range tq and the weird idle. I only got the 258's because they were drop in, with maintained mid-range and increased upper range. These don't seem to be as "all around good" as Tomei sold them as....

[Def]

You will lose some really low end torque, like 1-2.5k RPM with mild cams like that, but beyond that it should start to pull ahead of stock cams. Losing torque in the 3-5k RPM range sounds like you got a cam a tooth off.

Easiest way to do a cam swap is zip tie the chain to the gears, take the gears off, then bolt them to the new cams (assuming your timing was good from the start).

[GLoBaLReBeL420]

You will lose some really low end torque, like 1-2.5k RPM with mild cams like that, but beyond that it should start to pull ahead of stock cams. Losing torque in the 3-5k RPM range sounds like you got a cam a tooth off.

Easiest way to do a cam swap is zip tie the chain to the gears, take the gears off, then bolt them to the new cams (assuming your timing was good from the start).

Cam tooth is not off for sure. (Just re-checked all the teeth and pins)

I use the zip-tie method when I did the shaft swap out, and I counted in-between, and it hits 15Degrees on the dot with my timing gun. So, I know my timing is dead on I just don't know if there's something else causing me this loss of tq/power around 3-5K. Its driving me insane!!

[Kingtal0n]

you need to degree the cam. It might just be a different cam than it says on the box. or whatever

[GLoBaLReBeL420]

you need to degree the cam. It might just be a different cam than it says on the box. or whatever

I thought that as well, but when I put them in I verified the model of the cam shafts on each cam itself before installing. (Always gotta be sure)

I'm looking into degreeing the cam but that's like another $150 on top just to test them out (might not even fix anything).

I'll probably end up doing it, I'm just hoping to find something else as the problem before going that far to find out.

Anyone in South Bend,IN want to help me out :-)

[Kingtal0n]

Make your own degree wheel.. print out a circle on the computer and glue it down to some wooden or plastic circle piece you cut to fit then bolt it to the engine. then use a coat hanger as a pointer. All you need now is dial indicator like $10~ from harbor freight?

[GLoBaLReBeL420]

Make your own degree wheel.. print out a circle on the computer and glue it down to some wooden or plastic circle piece you cut to fit then bolt it to the engine. then use a coat hanger as a pointer. All you need now is dial indicator like $10~ from harbor freight?

I'm going to be totally honest and say I've never had to do this before. But, I am putting it together and will hopefully be able to figure it out. If anyone is out in South Bend,IN that can help, beers are in it for ya ;)

[Mysterious Driver]

Did you ever figure out the issue? I just ordered these cams earlier this week and will be getting them in and retuned in a couple of weeks.

[stevenrapids]

Anybody else run these and have any positive feedback? I ordered a set to run with a 2871 setup, but there hasn’t been much info available on them.

[Kingtal0n]

Anybody else run these and have any positive feedback? I ordered a set to run with a 2871 setup, but there hasn?t been much info available on them.

back in the day 05~ i tuned a bunch of sr with 256 264 272. They all do the same basic thing (it shouldn't be a surprise or response from someone about "what" the cam does)

thing is, the way they make cams today is different. Some companies do it wayyyyy different, materials and methods. So your question isn't one of how the cam "works" but rather how it was made, what materials were used, who cut it, how did that part go. Is it safe to use in your engine. Do the lobes match up with the cam card. Quality control.

so you can't easily ask a blanket question like that. Sure maybe from 05-08 the quality control was amazing but in 2012-2015 the manufacturing for the same exact grind was done somewhere else and its shit. or something like that

These days I would only buy a cam brand new directly from JWT or Tomei or HKS or Greddy. And use the matching valve spring and recommended valve hardware.
For some engines it doesn't matter but when it comes to sr20 I don't like to mix and match valve spring/cam manufacturers unless I am absolutely sure I need the extra pressure.
And then cross ur fingers.

[240boosted]

my car reads super low with haltech iq3 and but i have tomei 260 and i was pulling 14 cant find a leak at all

[dct223]

I just installed these on my s14 SR. Yes not much info about people running them.

I got the Tomei USA 258 set for s14/s15 SR.

Some info for me, S15 turbo. Still stock ECU, Stock 370cc injectors and have the basic bolt ons, exhaust manifold, elbow, downpipe, exhaust etc. 10psi

I'm still driving it easy to break in.

So far a little loss of torque in low end but it kicks in pretty good on mid range. I haven't redlined yet, going to drive it a bit more before I do but I can tell the power comes on strong. Idle is pretty stable, a little lumpy and rough but that is to be expected on a step 1 cam.

Only question I have that I haven't found answers to... On cold start, my SR hesitates a bit in the revs. Once it warms up it seems fine. I know I'm still on stock ecu. Anyone else experience this on cold start?

Don?t have any vacuum numbers but nothing seemed out of the ordinary other than a more lumpy/rough idle.

[dct223]

Just a follow up

Seems like my vacuum at idle for the tomei 258s match what some already posted.

Idle is approx -0.51ish bar on my defi advance boost gauge.

Cam isn?t off a tooth. It?s timed correctly at 15deg.

[stevenrapids]

Got mine installed and pull around 15 inHG at idle once warm. haven't gotten it all back together after paint to do a test drive, but they seem to be in-line with what others have stated so far.