So far the 4.9 is still bone stock (with the exception of the supercharger and intake of course) ....The injectors are still stock... The rising rate regulator was able to squeeze out enough fuel for 7 psi boost
I think weakest point on the 4.9 is valve springs and weak aluminum rocker arm rails The valves will float at higher rpm, especially with boost. The threads strip out on the aluminum rocker rails at high rpm. I already have stiffer valve springs and steel rocker rails.... just haven't installed them yet
I think the bottom end is plenty strong enough for 7-8 psi boost....I've never heard of a 4.9 with a blown bottom end more worried about blown head gaskets.... the 4.9 has floating cylinders.... When the heads are removed, the cylinders are loose and can be removed with your bare hands.
Also worried about breaking the transmission. I have broken a couple of Isuzu 5 speeds back when my 4.9 was naturally aspirated... My current tranny is the Getrag 282.... and it has held up well for a few years now.... But now it has to deal with a boosted engine.... I hope it continues to hold
Been driving my supercharged 4.9 fiero on a daily basis lately.
some observations I have made....
I noticed it is very octane dependent. I have to run at least super unleaded gas to keep it knocking to much Adding octane boosters helps even more...With a good quality octane booster, I can run full advance (MSD retard set to zero) .... with no octane booster, I have to adjust the MSD to a more retarded setting to keep it from knocking (and less power)
I also noticed that temperature has a considerable effect. If it is cool outside the car runs great It its hot, it runs more sluggish especially after the engine warms up. No intercooler, no water injection yet
I have had no problems with the belt at all.... It does "chirp" if you slam on the throttle... but belt hasn't fallen off yet.
The supercharger is way louder than I thought it would be.... I guess because of the 3 inch undersize pulley and large 4 inch intake piping ... sounds cool, but attracts attention when I floor it.... Its louder than the exhaust at full throttle....and my exhaust was loud to begin with (cat only, no muffler) No noise at all from the supercharger at idle or cruise.
I can not rev it much beyond 5000 rpm... because the valves start to float with the stock 4.9 valve springs. I know this because about a week ago I pushed the engine beyond 6000 rpm at full throttle... and noticed a ticking afterward that wouldn't go away. I thought I broke something. So I pulled off the rear valve cover... but didn't see anything broken. I went ahead and started the engine with the valve cover off and noticed that one of the rocker arms wasn't rocking. The pushrod jumped out of place. So I replaced that pushrod with another and put things back together and the engine is running fine again. I have stiffer valve springs ready to go...but need space to install them on the motor. I should have done this when I had the motor out of the engine bay during my clutch change.... Duh!!!
Good to hear it's running ok... get some dyno results so you know what AFR you're actually running.
Temp dependence is very much normal for a forced induction engine without good engine management.
I just remembered something.
The reason that most everyone's Allante intakes ran rich was because the IAT sensor was in the upper plenum, and not in the lower intake like the Deville. (The ECM was looking for much warmer air than it was getting.) Changing to the Allante IAT map pretty much fixed the problem.
Where is your IAT? If you can move it to somewhere "after" the supercharger, and switch back to the DeVille maps, it might help. Or not.
The point is... That one map makes a huge difference in how the engine runs.
The reason that most everyone's Allante intakes ran rich was because the IAT sensor was in the upper plenum, and not in the lower intake like the Deville. (The ECM was looking for much warmer air than it was getting.) Changing to the Allante IAT map pretty much fixed the problem.
Where is your IAT? If you can move it to somewhere "after" the supercharger, and switch back to the DeVille maps, it might help. Or not.
The point is... That one map makes a huge difference in how the engine runs.
I reinstalled the IAT on the supercharger... on the intake side. I didn't install it on the lower plenum because I felt it would get an abnormally high temp reading there. But I may try moving it there later.... next time I need to remove the supercharger.
The engine runs very good... No drivability problems at all. Just gets sluggish performance when hot
Originally posted by MaxCubes: I reinstalled the IAT on the supercharger... on the intake side. I didn't install it on the lower plenum because I felt it would get an abnormally high temp reading there. But I may try moving it there later.... next time I need to remove the supercharger.
The engine runs very good... No drivability problems at all. Just gets sluggish performance when hot
Are you using the Deville IAT table? Or the Allante table.
I have stock, as well as modded versions of both. I can send you anything you'd like. It'll still be a crapshoot, and I assume no responsibility... yada, yada yada.
Are you using the Deville IAT table? Or the Allante table.
I have stock, as well as modded versions of both. I can send you anything you'd like. It'll still be a crapshoot, and I assume no responsibility... yada, yada yada.
That is very nice of you. +++
But I am running a 305 tuned port ecm ( aka 1990-1992 Camaro Z28 5.0).... slightly modified
Max just disabled some functions I didn't want like VATS, EGR, rev limiter, etc. ...other than that, a stock AXXD prom
I used AXXD to model some IAC funtions for my mustang. One thing to consider is the TPI cars used a MAT (instead of an open element IAT) and installed in the lower intake. If you are using an IAT then you will need the "inverse lookup table" bit enabled, this needs to be done to model the airflow into the engine. I have been working with the MAT comp table to help make fuel delievery a little more accurate, the inverse lookup table has also been reworked by other tuners and works really well on both my fiero and mustang. If you want those LMK. HTH!
I used AXXD to model some IAC funtions for my mustang. One thing to consider is the TPI cars used a MAT (instead of an open element IAT) and installed in the lower intake. If you are using an IAT then you will need the "inverse lookup table" bit enabled, this needs to be done to model the airflow into the engine. I have been working with the MAT comp table to help make fuel delievery a little more accurate, the inverse lookup table has also been reworked by other tuners and works really well on both my fiero and mustang. If you want those LMK. HTH!
I assumed IAT and MAT was the same thing... I stand corrected. I am using a MAT sensor... Not an open element IAT My wiring harness has no provision for an IAT.
.... I didn't realize that it was installed in the lower plenum on the TPI engine....I assumed it was in the upper plenum, Duh !
I will tap a hole for this sensor in the lower plenum next chance I get....
I looked into the BAUJP prom (modified AUJP prom for boost)...lots of talk about it on the F-body/3rd gen forums .... but it is calibrated for the 350 TPI engine ( I guess F body lovers don't boost 305's much)
So I decided to use external fuel and ignition modifiers for boost management.
[This message has been edited by MaxCubes (edited 06-07-2013).]
I assumed IAT and MAT was the same thing... I stand corrected. I am using a MAT sensor... Not an open element IAT My wiring harness has no provision for an IAT.
.... I didn't realize that it was installed in the lower plenum on the TPI engine....I assumed it was in the upper plenum, Duh !
I will tap a hole for this sensor in the lower plenum next chance I get....
I looked into the BAUJP prom (modified AUJP prom for boost)...lots of talk about it on the F-body/3rd gen forums .... but it is calibrated for the 350 TPI engine ( I guess F body lovers don't boost 305's much)
So I decided to use external fuel and ignition modifiers for boost management.
There was someone working on B_AUJP years ago but AFAIK it wasnt released? Can you share it with me?
It shouldnt require much effort to set up the bin to work with your engine. Off the top of my head the cylinder displacment/injector size scalers should get it in the ballpark. If youre using a 305 memcal/knock filter that would closely match the 4.9.
The connector for the IAT should be the same, plug and play.
After the second run I had a ticking noise again. Damn push rod fell off again, I guessed On my way home, the ticking got louder and the engine ran rough
This morning I removed the valve covers. This time the damage was a bit more extensive... two rocker arms were loose. The studs that held them got pulled out from the rocker rail Its true....the 4.9 aluminum rocker rail is a weak point !!!
Needless to say, the engine cradle is coming back out again... No room to do this kind of work with the engine in the Fiero. I will be installing the Allante STEEL rocker rails...and stiffer LT1 valve springs to stop the valve float I'm too scared to change the heads. I wanted to install my ported heads... but there are no replacement head bolts for the 4.9.... and worried about damaging the head bolt threads deep in the aluminum block. I think I will leave the heads alone.
....will relocate the MAT sensor as previously discussed. And will be installing larger injectors. (from the stock 19lb... to 24lb.)....that way I don't have such high fuel pressure during max boost. They say injectors start malfunctioning above 75psi fuel pressure.
I will probably redo my exhaust system... My current exhaust is two 2 inch pipes merging into a 2 1/4 single pipe...too small and restrictive for a supercharged engine I think and also so that I can properly place my wideband O2 sensor for my air/fuel ratio gauge... so I can accurately tune the fuel pressure
Will take some pictures soon....
For now, here is the A/F gauge I have...
[This message has been edited by MaxCubes (edited 06-09-2013).]
.... Needless to say, the engine cradle is coming back out again... No room to do this kind of work with the engine in the Fiero. I will be installing the Allante STEEL rocker rails...and stiffer LT1 valve springs to stop the valve float
Before you go to all that trouble, remove the decklid. I installed the Allante intake and rocker supports with the engine in the car. Removing the decklid will give you an amazing amount of room.
Will the LT1 springs fit, within the parameters of the the stock valvetrain? (Thinking "spring diameter" and "coil bind" issues.) I've been curious (can't say I've done any real research) about something to replace my stockers without doing any other head work.
Before you go to all that trouble, remove the decklid. I installed the Allante intake and rocker supports with the engine in the car. Removing the decklid will give you an amazing amount of room.
Will the LT1 springs fit, within the parameters of the the stock valvetrain? (Thinking "spring diameter" and "coil bind" issues.) I've been curious (can't say I've done any real research) about something to replace my stockers without doing any other head work.
I'll remove the deck lid and try. I know I can get the rocker rails installed fairly easy, but I need more room to change the valve springs with the valve spring compression tool. Its hard removing and installing valve springs on a head that is still bolted to an engine... Even harder in a tight engine bay.
In a Melling engine parts catalog is where I found out LT1 valve springs may work on a 4.9.... Both have about the same solid height.... The LT1 springs are a tiny bit smaller in diameter... but are quite a bit stiffer than the 4.9 springs The LT1 valve springs must be from an F-body or Corvette.... Impala SS and Roadmaster LT1 springs are not the same (too narrow for the 4.9)
A few months ago I found some valve springs from a 1996 Camaro Z28 in a local junkyard. I removed them and installed them on an extra set of 4.9 heads I have lying around. They fit pretty good... no binding
[This message has been edited by MaxCubes (edited 06-10-2013).]
I wouldn't even remove the decklid, just remove the rear cradle bolts and loosen the front two and drop the rear of the cradle about 4-6". Should give you plenty of access to remove the valve covers and install the rocker arm bridge. Back when I had a 4.5, I pulled a rocker stud from the bridge as well... definitely need the steel version if you plan to rev over 5K.
In a Melling engine parts catalog is where I found out LT1 valve springs may work on a 4.9.... Both have about the same solid height.... The LT1 springs are a tiny bit smaller in diameter... but are quite a bit stiffer than the 4.9 springs The LT1 valve springs must be from an F-body or Corvette.... Impala SS and Roadmaster LT1 springs are not the same (too narrow for the 4.9) ...
I looked on Rockauto, after I posted before. They show the LT1 springs as discontinued. It was a Sealed Power part #. I hope I'm wrong. I didn't spend a lot of time looking elsewhere, however.
Went to the local drag strip here in El Paso last night (Friday)
Did two runs on the quarter mile.... I wanted to do more, but it was packed with racers.
First run was 13.10 and second was 13.32
I was hoping for 12 second runs.... oh well
quote
Originally posted by MaxCubes:
Traction was not so good with street tires... Yes in 4th gear at the end of the quarter mile. 107mph on first run... 105mph on second run.
What were your short times? I ran 12.86 @ 106 with a 1.92 sixty foot time with my stock Northstar. Your trap speeds show you have the HP... just need to get the E.T.
quote
Originally posted by MaxCubes:
Needless to say, the engine cradle is coming back out again... No room to do this kind of work with the engine in the Fiero.
quote
Originally posted by MaxCubes:
I'll remove the deck lid and try. I know I can get the rocker rails installed fairly easy, but I need more room to change the valve springs with the valve spring compression tool. Its hard removing and installing valve springs on a head that is still bolted to an engine... Even harder in a tight engine bay.
quote
Originally posted by fieroguru:
I wouldn't even remove the decklid, just remove the rear cradle bolts and loosen the front two and drop the rear of the cradle about 4-6". Should give you plenty of access to remove the valve covers and install the rocker arm bridge. Back when I had a 4.5, I pulled a rocker stud from the bridge as well... definitely need the steel version if you plan to rev over 5K.
I removed the decklid and lowered the rear of the cradle and was able to get the forward cam cover off my Northstar in the car. You should be fine with a 4.9.
I @$$ume you're planning to pressurize each cylinder in order to hold the valves up while you're changing the springs? What valve spring compressor do you have?
What were your short times? I ran 12.86 @ 106 with a 1.92 sixty foot time with my stock Northstar. Your trap speeds show you have the HP... just need to get the E.T.
I removed the decklid and lowered the rear of the cradle and was able to get the forward cam cover off my Northstar in the car. You should be fine with a 4.9.
I @$$ume you're planning to pressurize each cylinder in order to hold the valves up while you're changing the springs? What valve spring compressor do you have?
My 60 ft was 2.35 and 2.43... poor traction, and my heavy foot to blame
Yea, good idea guys... I will lower rear cradle and remove the deck lid... should be plenty of room after that
This is my theory... I will change two springs at a time on each cylinder when the piston in that cylinder is up ... at the point when the exhaust valve has closed and the intake is about to open (cam overlap) That way the valves in that cylinder will not fall into the cylinder enough to be lost
The compressed air method is probably the preferred method....but...
I have removed springs from heads still bolted to the block at the junkyard without an air compressor... because you cannot bring an air compressor to the junkyard.
This is the trick...
Lightly tap around the retainer to loosen things up... Don't hit the tip of the valve Compress the valve spring with your compressor tool. Use a magnetic pickup tool to easily remove the little retaining locks
I removed all 16 springs from an LT1 engine this way
[This message has been edited by MaxCubes (edited 06-12-2013).]
I will change two springs at a time on each cylinder when the piston in that cylinder is up ... at the point when the exhaust valve has closed and the intake is about to open (cam overlap) That way the valves in that cylinder will not fall into the cylinder enough to be lost
quote
Originally posted by MaxCubes:
Lightly tap around the retainer to loosen things up... Don't hit the tip of the valve Compress the valve spring with your compressor tool. Use a magnetic pickup tool to easily remove the little retaining locks
I understand why you need to do that in a junkyard, BUT in your own garage where you have all your tools handy, why on earth would you do it the hard, risky way? Life's tough enough already... don't go out of your way to make it tougher.
I understand why you need to do that in a junkyard, BUT in your own garage where you have all your tools handy, why on earth would you do it the hard, risky way? Life's tough enough already... don't go out of your way to make it tougher.
your right.... I need to find that adapter that screws into the spark plug hole so I can connect my air hose
I looked on Rockauto, after I posted before. They show the LT1 springs as discontinued. It was a Sealed Power part #. I hope I'm wrong. I didn't spend a lot of time looking elsewhere, however.
