Saabscene Saab Forum - Saab Technical Information Resource banner
1 - 20 of 23 Posts

·
Registered
Joined
·
1,597 Posts
Discussion Starter · #1 ·
Now in jubilant spirit with my aero running well -I now plan to remove the heatplate across the inlet manifold to get a bit more top end oomph. I have my new inlet manifold gasket at the ready and have read a few other posts on this but have the following Qs

1) Other posts suggest using a stack of M8 washers to take up the space left by the heatplate. Has anyone bought shorter inlet manifold bolts from a non heatplate model and used them? If the washer concept is OK then I'll go with that.

2) Do I use gasket sealant on the new gasket? If so what is advised? (haynes doesnt mention the use of any.

3) Has anyone actually measured the difference in power before and after removal?

4) Anyone had any problems due to removal of the heatplate? Although I read that Abbot remove them as and when they get one.

I know that the heatplate affects only a few cars(1996-and some of 97 only?) - and even fewer people will have removed them from an aero - but appreciate any feedback before I have a bash at this at the weekend.
 

·
Registered
Joined
·
430 Posts
I had my heatplate removed when my car was having a service as I couldn't be chewed to do it myself.So I'll answer the questions as best I can.

1. The Saab main dealer fitted new shorter bolts when they did mine , an expensive luxury ,genuine Saab bolts. I could measure the thickness of my heatplate and the length of the old bolts & let you know what length bolts you need.
I think the thread is M8 but I can check tommorow, they'll be easy to get from a fastening suppliers or you could get stainless ones from a chandlers, either way they'd be lots cheaper than Saab originals.(£2.48 each plus vat! ) I've bought whole cars for less than those bolts cost.

2. I'm pretty sure you don't need gasket compound of any sort.

3.I didn't & I fitted a speedparts ECU the day after so I'll never really know, but it certainly isn't any slower. The heatplate elements , although aerodynamically sleek, still mask quite a large area of each intake port. Removal has got to allow the engine to breath easier.

4.No problems at all, apart from trying to find something useful to do with an old heatplate. Perhaps I could sell it on Ebay to someone who lives where it's cold.
 

·
Registered
Joined
·
1,597 Posts
Discussion Starter · #3 ·
thanks Whitesaab - I think I'll just order a single bolt for a non-heatplate model and use this as a reference to buy the rest - last thing I want is a leaky inlet manifold. You don't happen to have a note of the saab bolt part number used do you?

As for removing the heatplate - from what I have read it wont make much difference lower down - but as the turbo boost is 'tapered' at high revs, the boost should be held a little higher...I'll soon find out.
 

·
Registered
Joined
·
1,597 Posts
Discussion Starter · #4 ·
One other question I meant to ask was whether you should drain the coolant level down a bit first when removing the manifold- as I am concerned about getting coolant into the engine inlets.
Or can this not happen by design? (Haynes doesnt mention draining of coolant either)
 

·
Registered
Joined
·
1,597 Posts
Discussion Starter · #5 ·
Found this on the Saabnet site - answers most of my questions.

"
1. There was no "overboost" function or anything like it introduced in 1996. I know for a fact that the Aero software was unchanged from 1994 to 1997 (even 1998 if we include the "Classic" as it was called here). What I guess you're referring to is the momentary boost surge that you may get when you apply the throttle briskly. That has more to do with the fact that in the software boost levels can be "programmed" in two different ways. For instance, the program could (at a certain rpm, gear and throttle position) have "1,0" bar or "1,0 bar+", depending on whether the software is supposed to stabilize boost or continue to increase boost beyond that point. I guess that's what you're experiencing.

2. Heat plates is an interesting "phenomenon" that Saab introduced in 1996 as a measure to reduce emissions at cold start. It's an electrically heated "plate" that has "tentacles" that sit in the intake channels and heat the intake air. Naturally they seriously reduce airflow through the intake and, for performance reasons, should be removed.

Determing if you have heat plates can be done in any of the following ways:

1. Standing in front of the engine bay, check the fuse box on the right. If it has any referral to "HEAT PLATE", well you have heat plates...

2. Check between the engine block and the intake. The heat plate is like a 7-8 mm gasket with an electrical wire attached on the driver's side.

3. Check your boost @ 5500 rpm. If it's 0,82 bar you have heat plates, if it's 0,69 bar then your car doesn't have 'em...

Removal is easy. Remove intake. Unscrewing the bolts is a bit of a pain as access is limited, but it's no worse than many other things we willingly undertake... Just buy a new gasket from Saab and remember to untap some of the coolant as this can risk get into the engine otherwise... I took the opportunity to change coolant while I was at it. It REALLY improves performance, especially in my car which has an upgraded ECU. "
 

·
Registered
Joined
·
430 Posts
The part number for the bolts they used on my car was 7970015, though the description on the invoice is 'nut'

Saab epc shows it up as a 'screw' .

They are very nice, though pricey and they have those nice integrated washer type heads.
 

·
Registered
Joined
·
8,216 Posts
Originally posted by faero:
[qb]Found this on the Saabnet site - answers most of my questions.[/qb][/b]
That was my original conversation with, I think, Karl in sweden about heatplates, back in the days when I was allowed to post on Saabnet


Two comments - although it's irrelevant to the heatplate issue, we established later that Karl was mistaken about the Aero software being unchanged from '94-'98. There was a momentary overboost function added to the Aero in '96.
Secondly, Karl's reference to an electrical cable on the "driver's side" refers to the left-hand side, where the driver sits in Swedish models.


When I asked my dealer's parts guy about using the non-heatplate bolts, he said that he couldn't be sure they would fit properly because the manifold for non-heatplate models was also different. It was he who recommended packing out with washers.
 

·
Registered
Joined
·
1,597 Posts
Discussion Starter · #9 ·
Ok - Finally took the heatplate out of my 1996 Aero (after confirming it was there!) so thought Id share my experiences:

I'll not repeat previous useful comments but I reckon these are the most useful
1) I tried to do the job initially without removing the Throttle body from the inlet manifold - partly due to lack of the correct tools. I ended up having to take this off after getting a nice little UJ.

2) I cleaned up the engine and manifold gasket mating surfaces with light scraper (careful!) +emery paper -- seemed ok once I'd finished.

3) Watch you dont kink/damage the pipe on the OS of the inlet manifold going to the MAP sensor - rather sensitive little pipe.

4) Putting in the new bolts I used 5 additional M8 washers to space out where the heat plate would have been - I ended up tacking them together with superglue(!) so that they wouldnt fall off the bolt en route to the more fiddly bits - youll need a 200mm extension to reach the bolts.

5) Reckon I removed about 4 litres of coolant from the system just to be safe.

Test drive:
After checking warm up and coolant were ok (after the warm satisfaction that it actually started) went off for a spin.
The car basically felt more eager (quite considerably)- flooring in 3rd to about 5500rpm , it was frantic all the way as opposed the normal wall of torque that 'fades' a little towards the line. I cant quantify the exact change but it felt like a good 10-15bhp along with a sharper response. I suppose that is the result of getting 0.82 bar as opposed to 0.69 at top whack....I also reckon my IPT airfilter (only other mod) will start to be of more use given the higher volume of air required at higher rpm.
Anyway - job done,cheers for the info.
 

·
Registered
Joined
·
250 Posts
Faero,

Just to clarify: were your new bolts the shorter ones? If so, you shouldn't have needed to use extra washers, just one on each bolt would do.

I did a heatplate removal on my 2.3 LPT two Sundays' ago, and like you, I can confirm there is a definite improvement. Nothing as earth-shattering as you might gain from a HPT, but I now experience the following:
- much better throttle response from 2.5K to 3.5K revs, particularly in 3rd and 4th.
- prior to removing the heatplate, the car would 'bog down' a little too easily when in high gear at low speeds. I know the box is highly geared, but the bogging down no longer happens, and I can get away with pulling smoothly from low speed more often in 3rd, which is great - less gear crunching.
- more momentum sustained uphill, for a given gear.
- I am consistently getting a full 1 mpg more on a mix of country runs and M-way (steady 80 mph) - currently 36.4 mpg. This being based on 1,400 miles driven since the previous Sunday.
- the throttle pedal seems physically lighter (strange this, since no mechanical changes were made to the throttle body, but it is lighter).

So, no claims to break the sound barrier, just more relaxed motoring in the mid-range, plus better economy. Oh, and the car doesn't seem to 'shunt' so much in slow-moving traffic (useful for my M25 runs!). All in all, I'm very glad I did the operation.

Enjoy the extra hp, Faero!
 

·
Registered
Joined
·
1,597 Posts
Discussion Starter · #11 ·
After much debate I kept the longer bolts and used the washers...only downside is I couldnt get the torque wrench in to do the top inlet bolts precisely..but they are pretty close to spec(I reckon!)
As for the performance - in my blast down the M4 to Heathrow last night, I could swear that the car picks up from even very low rpm much better and it flies in 3rd. This low end pickup goes against the fact that only the high rpm boost should be affected, but nonetheless, there is a definite sprakle and urgency across the board that wasnt there before - maybe that's just normal to those non heatplaters! Or maybe the Ecu has other alterations to fueling etc. as well as the boost levels??
Next stop -check the base boost is set OK, maybe there's a little more sparkle to come yet.
 

·
Registered
Joined
·
2,599 Posts
I removed heatplate from my 2.3T auto a few weeks back - didnt fancy paying Saab for the shorter bolts, also didnt fancy packing out with washers so I simply cut down the original bolts, filed a chamfer on the bottom of each and bolted it all back up.
 

·
Registered
Joined
·
250 Posts
Adrian,
What improvements - if any - have you noticed? I'm just keen to know if people are consistently saying the same thing about post-heatplate benefits (then I know that my mind isn't playing tricks with me!)
 

·
Registered
Joined
·
1,245 Posts
Saab-jager wrote:
- the throttle pedal seems physically lighter (strange this, since no mechanical changes were made to the throttle body, but it is lighter).
 [/b]
The throttle pedal won't be any lighter it's just that the car is now more reponsive with more go for less throttle giving the impression that the throttle is lighter
The converse of this used to be carried out by motorcycle mechanics. When doing a service they would oil the throttle cable. The lighter action convinced the rider that the bike was now much faster after it's service.

Having read all these glowing reports of heat plate removals, I think it is about time I did away with mine. The only thing that has put me off up to now, apart from the work, is having to waste a couple of hours on a saturday morning doing a 60 mile round trip to the dealer to buy an inlet manifold gasket.
 

·
Registered
Joined
·
2,599 Posts
Adrian,
What improvements - if any - have you noticed? I'm just keen to know if people are consistently saying the same thing about post-heatplate benefits (then I know that my mind isn't playing tricks with me!)
--------------------------------------------------------------------------------[/b]
Well to be honest its hard to really say, I did the head gasket at the same time, re-lapped valves etc. Car certainly sounds great particularly at the top end. Is it quicker - yes compared to when the head gasket was leaking at No1!, how much is down to plate removal I can not say. However, having looked at the restriction it creates in the inlet manifold it can only help
by removing it.
 

·
Registered
Joined
·
1,597 Posts
Discussion Starter · #18 ·
just to update that mpg has improved too. Its now running just over 33mpg compared to just over 31 before. Done about 500miles to check accurately and the commute and conditions/traffic are identical to previous - in fact its a bit cooler now so I'd expect its using a little more choke from cold too.
Cant be bad.
 

·
Registered
Joined
·
1,908 Posts
Following renewed interest in this topic, and a v-quick search on 'Heatplate removal' thought I'd raise this one back to the top of the pile. Lots of useful info.

Can anyone who has done the job advise how long it takes to remove heat plate?

It's all a bit like having your appendix removed: Completely surplus to requirements,[/b]
Of course, the surplus to requirements bit is a myth ( as was the other 20+ body parts which were once believed to be redundant ). It is proven to play a role in the breakdown of cellulose. Not sure where the appendix is found on a 9000 though!
 
1 - 20 of 23 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top