those with out the secondaries?????
 

i went to coreys in dec to remove my secodaries, get retuned and his headers,instead of the stainless works . didnt get a chance to do headers, his brother was getting married that sat . but did get the secondaries done and a new tune . when i had it tuned after putting on the stainless works 3 yrs ago she made 383 on the dyno . car also had a corsa on it . this time with my 3in x pipe then 23/4 factory tubing into 3 in super turbos with dual 21/2 in exits made 399.plus my highway mileage seems to improved by about 2 mpg. .the runs were 3 yrs apart and figure the exhaust might have made some of the improvement .car also seems to have alot better midrange .what are your guys experiences ..please tell me your thoughts on your cars . can hardly wait for the first weekend in feb to try at the strip .

Re: those with out the secondaries?????
 

i've been trying to drive a stock cid non ported car without secondaries for years. I've been kicking around the idea of pulling mine via tune for years

Re: those with out the secondaries?????
 

Before I bought a ZR-1 to drive, I joined the Registry and read everything I could here. At the time, it seemed that there were several people with vac leaks. Chasing leaks, pulling plenums, etc.

When Pete did my motor, I decided that I wanted the secondaries removed at that time. It just made sense to me. Still does. Haven't chased any vac leaks either.

Love my car. Thanks, Pete!

Re: those with out the secondaries?????
 

Same stock cid and non ported here.
Fixed a plugged check valve and hole in the tube in 99 and the
secondaries ran fine until last year when the pump got a rebuild.
Secondary works fine and I LOVE being able to take the power key out. It's a great conversation piece.

Re: those with out the secondaries?????
 

As part of Marc's 510 package he removed my secondaries, pump, hoses etc. Since we are adding headers we also removed the AIR pump and pipes (it was born a California car). I am keeping all the parts in case the next owner (after I am dead and gone!) wants to restore the car to stock. Removal seemed like a good idea since we no longer have emmisions testing in Illinois for our cars. Marc said it doesn't adversely affect the operation of the car, keeps the secondary valve clean, is less work to put back together and means fewer future headaches. Seemed to make sense to me. I look forward to trying it out next month--weather permitting. --Bob

Re: those with out the secondaries?????
 

Dyno results:

LOTS of varibles there...

The accuracy of the atmospheric parameters entered into the dyno is a factor
Air temp and engine temp contribute subsatially to dyno results,
Tire pressure, types of tires too, for that matter
Temp of oil in the transmission
(etc)

All of these things can increase the % of ambiguity in test results. There's no getting around the possibility for some of the change being due to some (or more) factors mentioned. However, a 17 hp change would appear to reach well beyond the normal delta one might anticipate in comparison due to common errors in instrumentation etc.

Pete did some recent dyno comparisons of a Corsa vs. other schemes (On Dave Johnson's car, if I'm not mistaken) and found the Corsa to cost an amount of rear wheel hp amounting to a significant portion of the gain you experienced by (as I understand what you're saying).

Bottom line - a 17 hp lift is significant. Congratz!!:thumbsup: The X-pipe no doubt is contributing to some gain, but the trail starts growing cold, far as comparing results by others, as the number of variables changes (pipe sizes and especially changes in diameters throughout).

Gas mileage:

Changing the tune can have a significant effect on mileage either way - OR NONE, depending (again) on the specifics of the tune. In my case, before and after my "500" package (including removing the secondary port throttles), mileage was still within the margin for error; about 26.5 on cruise control at about 72.

I did that check last summer before gassing up before going on a mild spirited cruise through some twisty roads in NW IL. There was many WOT spurts and a sizable amount of third gear stuff through the twisties. At the end, some 200+ miles later my mileage was still above 24, which surprised me a bit. Around town with stop and go traffic, I get about 18. (You can see my setup in my signature at the bottom of the post;))

Midrange torque:

My stock 90:

http://i185.photobucket.com/albums/x...20-08Large.jpg

After the 500 package:

http://i185.photobucket.com/albums/x...T510-19-10.jpg

I picked up approx 97 hp and approx 40# of torque, but not sure if that answers the quesiton. But, far as removing the secondaries goes, I like the improvements; the throttle response, and the fact both intake valves get constantly cleaned. I can't say what (if any) difference there is in hp or torque following their removal, but their not being there to impede the air flow at the core of the column, can't be bad. Plus, parts that don't exist seldom break, and they don't cost much! I saw no need to have 'em and was one of the first things I got rid of, and never looked back.

P.

Re: those with out the secondaries?????
 

Well, that's two plenum pulls at least, and coupled with an external pump issue, that's 3 good reasons to eliminate 'em :frown:

With the SPTs eliminated, the smart thing to do is bypass the switch - read: hard-wire it through to prevent the FULL POWER mode from intermittently or accidently being turned off. So, the switch becomes nothing but a conversation piece at that point...which is ONE LESS PIA deal with, far as secodaries go.

Just tuggin' on yer tail in fun, thar Scott!:p

P.

Re: those with out the secondaries?????
 

If you don't want to rip things out, then tie wrap the secondaries open and have the memcal burned for secondaries "always on".

Re: those with out the secondaries?????
 

i understand that there was 3 yrs between dyno sessions looking at the sheets the temps and humidity were very close 2% difference .i do feel that the corsa does cost some power compared to my current set up as my ets went down from a before best of 12.48@114.89 to a best of 11.94 @117.81 these results wee all at famoso dragway in bakersfield ca.i realize to some that may seem like a big difference for just an exhaust change but it was the only change i made .maybe the tune was a little rich with the corsa and going to my current setup brought it in line better . i had the same tune on both passes

Re: those with out the secondaries?????
 

i havent run the car at the strip with the secondaries removed .will report when i do

Re: those with out the secondaries?????
 

Mr Workman, do you notice the torque drop during low rpm cruising/driving? Looks like around 20-25 rwtq at 2000rpm. Does throttle response feel soggy down there?

peace
Hog

Re: those with out the secondaries?????
 

his 2 dyno sheets were stock and after his porting . i don't think he had the secondaries removed on the first sheet . on my car it seems that if anything there was better low end performance

Re: those with out the secondaries?????
 

The first is graph is stock. The second is w/ the secondaries removed AND full porting. There is no reduction of torque anywhere across the rpm range, comparing the "after" to the stock graph.

Not mushy or boggy at 2000 rpm at all, after the 500 hp mods. Absolutely love the way it handles/drives now - with the mods, w/o the secondaries.

P.

Re: those with out the secondaries?????
 

I think you're swapping the graphs? Wheel torque for the stock motor at 2000 rpm was about 275-280 (top graph). After the mods torque was at 300# @ 2000 rpm (bottom graph) and climbs from there.

Re: those with out the secondaries?????
 

marc pulled my secondaries when I had some troubles and the plenum needed to come off. he also cleaned up the injector housing porting a bit.

net result, no more HP but a noticeable difference in mid range and a bit better throttle response. real opportunity is if you pull the secondaries and open up the secondary ports in the heads.

not a good idea if you need to pass emissions. Graham told me that this is one of the reasons they are there. more port velocity, swirl, and less HC.

sure enough, with the secondaries (big cams and valves) I could previously get the car down to 98 HC, after the secondaries were removed, 140 was as clean as I could get

didn't really notice any difference in mileage. running at 14.7 stoich should be the same with one injector or two :)

definitely think it helps the car keep the secondary valves and injectors much cleaner as they are running all the time except for dead idle when the calibration cuts back to 1 injector as less than 1% throttle.

Re: those with out the secondaries?????
 

Yeah, buddy! The secondary runners going into the secondary throttle plates are are approx 36mm, but just past the throttle plates, the dang things cone down to much smaller than that in about the distance of 10mm before just as abruptly straightening out. Far as flow dynamics go, that's one area that can benefit from some time with a die grinder (and the heads don't even have to come off to do it either! Wow! What a difference removing some metal there made!

"Coning" the runner from the entrance to the valve guide @ ≈ 4% taper. this gets rid of two rather abrupt changes in angle to air flow past the port throttle area: Smooth taper.

http://i185.photobucket.com/albums/x...s/IH9Large.jpg

I'm digressing a bit, but here's and example of some "FBI" IH runners on a 90 - as part of a top end port&polish - well on it's way to 400 rwhp.

http://i185.photobucket.com/albums/x...es/ZR-1008.jpg


I often wonder what affect a special gasket - one tha blocks off the secondary runner - would have on emmissions tests. (Just asking out loud)

P.

Re: those with out the secondaries?????
 

Yes Paul, thats what I was doing, I crossed up the graphs. Thank you.

Sounds like other than emissions there really arent any downsides to removing the secondary throttles.

Some have stated their desire to retain the "power-key" function. Is there any way to accomplish this. Can the throttles be removed, and still have the primary injectors do all the fueling when in reduced power mode?

As Ron states, it is good to have the secondary injector firing in order to keep the valves clean. I'm not the type that would drive a whole lot without the secondaries firing.

peace
hog

Re: those with out the secondaries?????
 

putting in a gasket blocking off the secondaries would be an ez way to pass emissions, turn off the power key and away you go

my problem is that with the 234 cams, my hc were up at 98 even with the secondaries. VA cut the emissions standard to 48. very tough with cams

I actually want to try getting a chip burned for E85 (or pure alchy)

warm up the car on gas, drain it out, swap the memcal, and go through like a breeze.

I haven't found anyone local that can help me burn the chip. wouldn't be all that hard as I'd only need to run part throttle up to 30 mph (no wot ever)

the VA emissions standards are pretty tough