Well, whats the difference? Runner leanth?
here i will post some pics of the inside of one of my lt1s intakes
and Mini-Rams, if where looking at price why not just get a lt1/lt4 intake for 1/3 of the price of the mini ram?

heres the front shots

 

side shots

 

heres the inside of my lt1 looks smaller and has a hump, other then that basicy look the same (lt1s the bottom one in the pic)

 

Runners
Mini ram --------3.500”
LT1 ----------3.000”

 

Standard 23* heads

 

still cheaper to drill the holes on the intake

 

I think the remote thermostat is what turns most people off on it. I know I don't like it.

 

Did you happen to measure the runner cross sections of the HSR? I know the LT1 runners are 0.983"W x 1.892"H. If Holley is true to form, they've made them smaller to allow them to be bolted to lesser heads in the SBC family.

It seems that Holley went the wrong direction, since GMPT determined that the negligible/short runner was the key to the wide torque band afforded by the LT1 design. I suppose a half inch is no big deal, but still it's the wrong direction. I'm guessing that could be repaired by some port work in the HSR to break the edges of the upper ends of the runners to "undefine" them. Then again, the same thing can be done to the LT1 to shoten and detune them even more.

Have an LT4 intake to compare? That would be interesting.

 

Agreed. I don't particularly care for the double-decker thermostat in the LT1s, but I live with them. Once they're installed a bled or all air, it really doesn't matter.

For a comversion, however, the remove housing and hose does add to the price as one of those "hidden" costs. Those seem to come with every modification though.

 

do you own both of these intakes tony???

Jason

 

hey Jason, no i don't but i do have the lt1, i was looking into the Mini-Ram and i know you where too, i see no real difference between the too! so that's why i went with a LT1 intake,
As for the lt4 intake there isn't much difference the lt4 has higher ports 0.10" (2.5mm) the manifold TB ports are sized at 52mm instad of 48mm like the lt1, but both the lt1 and lt4s where fitted with 48mm TBs (go figure) but becuz of this it makes a aftermarket 52mm throttle bodie a popular performance bolt-on if you got a stock lt4, and that's pretty much all i know besides the fact the manifold was cast with additional material to allow safe machining of the ports to match the LT4's higher head ports, and LT4 intakes were also powder coated red to differentiate them from the standard LT1 manifolds,

 

LT1 vs LT4 ... What are the Differences?

While sharing the same bore and stroke, there is a LOT more to the 1996 LT4 engine than just a red intake manifold! What follows is a detailed listing explaining the technical differences between these two Corvette powerplants. What cannot be shown here is the "seat-of-the-pants" difference only a drive in an LT4 equipped Corvette can provide.

The LT4's horsepower increase and reliability at higher RPM's (compared to a standard LT1) is largely achieved through the following differences:

* New camshaft design
* Larger valves
* Roller rocker arms
* Revised Head design
* Head Gaskets
* Revised Piston Design
* Positive-twist top piston rings
* Fuel System
* Intake Manifold
* Roller timing chain
* Specially machined crankshaft
* Dual-mass front torsional damper
* Nodular iron main bearing caps
* Teflon rear crank seal


LT1 Engine

LT4 Engine

BASIC LT1 and LT4 SPECIFICATIONS

Specification LT1 LT4
Block, construction Cast Iron Cast Iron
Bore, inches 4.00 4.00
Compression ratio 10.4:1 10.8:1
Connecting Rods Powdered metal Powdered metal
Crankshaft Cast iron Cast iron with undercut and rolled fillets
Cylinder Heads Cast Aluminum, 2 valves/cylinder Cast Aluminum, 2 valves/cylinder
Displacement 350ci (5733cc) 350ci (5733cc)
Fuel system Fuel Injection, Electronic sequential port Fuel Injection, Electronic sequential port
Horsepower, factory rating 300 @ 5000 RPM 330 @ 5800 RPM
Main Bearings 4-bolt centers, 2-bolt ends 4-bolt centers, 2-bolt ends
Pistons Eutectic aluminum/silicon alloy Eutectic aluminum/silicon alloy
Redline, factory rating 5700 RPM 6300 RPM
Rocker Arms Conventional, stamped steel, 1.5:1 ratio Roller, forged aluminum, 1.6:1 ratio
Stroke, inches 3.48 3.48
Timing Chain Link chain, powdered-metal sprockets Roller chain, steel sprockets
Torque, factory rating 340 @ 4000 RPM 340 @ 4500 RPM
Torsional Damper Single mass Dual mass
Valve Diameter, inches 1.94 intake, 1.50 exhaust 2.00 intake, 1.55 exhaust
Valve Duration 279 intake, 276 exhaust 282 intake, 277 exhaust
Valve Lift, degrees .447 intake, .459 exhaust .476 intake, .479 exhaust
Valve Overlap, degrees 41 46
Valve Springs Round Section Oval section, higher closing force


LT1 and LT4 COMPONENTS & PART NUMBERS

Parts: LT1 Description Part # LT4 Description Part #
Camshaft See specs below 12551705 See specs below 12551142
Cap, (Retainer) valve spring 10212802 10212808
Connecting rods Powdered Metal 10108688 Powdered Metal 10108688
Chain, Timing Powdered metal butt link 10128485 Single Roller (made for GM by Cloyes) Steel 12555887
Crankshaft 12556307 Nodular Iron (Additional Machining) 12551485
EGR ? Overlap leaves EGR redundant ?
Gasket, Head 10168457 Composite w/ steel rings 12551488
Gasket, Intake 12524653 for higher ports 12528884
Head (L/R Same) 212 CFM flow 10168448 240 CFM flow Higher ports 12555332
Injectors 3.0gps 24lbs/hr 17124248 3.5gps 28lbs/hr 17124251
Intake Manifold 12552137 Higher ports 0.10" (2.5mm) than LT1 12550630
Knock Module 16177700 Less Sensitive to engine noise 16214681
Knock Sensor 10456287 10456287
Pistons 10159437 Shallower valve pockets than LT1 12551526
Rings, Piston Positive twist 12528817
Rocker arms 1.5:1 Ratio Stamped steel 10089648 1.6:1 Ratio Aluminum Roller 12557779
Shim/spacer under spring 10212809
Seal, Crankshaft 10206040 Teflon 10206040
Spring, Valve 85 lbs. (38.6 kg.) Seated 10206040 100 lbs. (45.4 kg.) Seated -260 lbs. (117.9 kg.) open 12551483
Sprocket, Cam Webbed 10206039 Solid (Add Mass) 12555885
Sprocket, Crank 10128346 12555886
Throttle Body Twin port, 48mm ? Twin port, 48mm ?
Valve, Exhaust 1.50" (38.1mm) Solid stem Weight:95 grams, 3.35 ounces 12550909 1.55" (39.4mm) Sodium filled stem Weight:75 grams, 2.65 ounces 12551313
Valve, Intake 1.94" (49.3mm) Solid stem Weight:110 grams, 3.88 ounces 10241743 2.00" (50.8mm) Hollow stem Weight:85 grams, 3.00 ounces 12555331



# NEW CAMSHAFT DESIGN...


The LT4's more aggressive camshaft profile compliments all the valvetrain upgrades. The cam has more lift, duration and valve overlap. Exhaust valve lift is .479" (12.17mm) (net is less .006" inch (0.15mm) lash), @ .050 (1.27mm) Lift, up from .459" (11.66mm) for the LT1, and the intake is .476" (12.09mm) (net is less .004 (0.10mm) inch lash), up from the LT1's .447" (11.35mm). Duration is also increased slightly on both exhaust and intake... 203 deg. Intake and 210 deg. Exhaust with 115 deg. lobe separation and 1 degree of retard. By increasing overlap significantly, it eliminated the need for an external exhaust gas recirculation (EGR) device.

CAMSHAFT SPECIFICATIONS ('96 model year)
(LT1 w/1.5:1 Ratio rockers and LT4 w/1.6:1 ratio rockers)

Engine Valve Lift @ .050"(1.3mm) Specification Engine Lobe Lift @ .050"(1.3mm) Specification
LT1 Intake .447"(11.35mm) LT1 Intake .298"(7.57mm)
Exhaust .459"(11.66mm) Exhaust .306"(7.77mm)
LT4 Intake .476"(12.09mm) LT4 Intake .298"(7.57mm)
Exhaust .479"(12.17mm) Exhaust .299"(7.60mm)
Engine Duration @ .050"(1.27mm) Specification Engine Lobe Separation Specification
LT1 Intake 205 deg. LT1 117 deg.
Exhaust 207 deg. LT4 115 deg.
LT4 Intake 203 deg.
Exhaust 210 deg.



# LARGER VALVES...


LT4 valves are 2.00-inch (50.8mm) Intake and 1.55-inch (39.4mm) Exhaust valves (as opposed to the 1.94 (49.3mm)/1.50-inch (38.1mm) combination used in the LT1) were made lighter to reduce inertial stress, both intake and exhaust valves are hollow and the latter sodium & potasium filled to improve heat transfer. Valve springs are stronger, with a higher installed seat pressure (100 lbs.in. for the LT4 vs. 85 lbs. for the LT1) and wide open pressure (260 lbs. on the LT4) to keep the valves following the camshaft's contours. Special valve springs, eliptical shaped instead of circular in cross-section (Larger horizontal cross section than vertical), allow a spring with a higher free height to be compressed more for higher operating pressures. LT4 Intake valves weight 85 grams. LT1 Intake valves weight 110 grams. LT4 Exhaust valves weight 75 grams. LT1 Exhaust valves weight 95 grams.


# ROLLER ROCKER ARMS


The LT1's stamped steel rocker arms exhibited ball galling at 6400 rpm, so modified Crane roller rockers were substituted in the LT4 with lock nut and set screws to replace the conventional ball and friction nuts. Shims were added to maintain the valve stem accurately and the stud slot widened. The roller axle reduces friction measurably, the 2 lbs-ft reduction increasing economy and responsiveness. The rocker arms also have a roller tip. The LT4 has 1.6:1 and LT1 has 1.5:1 Rocker Ratio.



The LT4's new valve springs are made from egg shaped wire for higher seat pressure and improved valve dynamics at higher RPM.




# REVISED HEAD DESIGN


The big difference in the heads is the intake and exhaust ports. Both are larger with bigger radius bends. The "short side" radius of the LT4's exhaust port in particular has been increased to reduce back pressure at higher RPM,s. A throat cut just past the exhaust valve seat also opens up the exhaust port. (Unshrouding valve). The Intake port volume has increasd by 25cc. Increased from 170cc on the LT1 to 195cc for the LT4. The flow through the heads have been increased from 212CFM (Cubic feet per minute) @ 28" (711mm) (LT1) to 240CFM (LT4).

The roof was slightly lowered and the walls were moved back slightly from the valves for better breathing, undercutting next to the exhaust valve thereby "unshrouding the valves." Revised port contours enhance air flow into and out of the engine resulting in increased fuel burning efficiency.



Combustion chambers are almost identical with a negligible .4cc increase in volume for the LT4 Combustion chambers at 54.4cc's.

Both the LT1 and the LT4 Heads accomodate 7/16" studs but the LT4 has larger 7/16 rocker studs. There are some reports of early LT4's with 10mm top threads. The LT1 studs are 3/8" on top and 7/16" bottom. GM part numbers are #3921912 for 7/16" LT4 and #1255216 for 3/8" LT1.



Shown below is a cross section comparison of the LT1 (photo A) and the LT4 (photo B) heads. The LT4 Intake port is 25cc larger than the LT1. The revised rocker cover rail is due to the taller intake port opening. Intake valve sizes are 1.94" on the LT1 and 2.00" on the LT4.



In the photo below, note the differences in the exhaust ports on the LT1 (photo A) and the LT4 (photo B). The short side-radius offer much smoother flow and the throat cut is slightly different. Exhaust valve sizes are 1.50" (38.1mm) on the LT1 and 1.55" (39.4mm) on the LT4. Also notice the LT4's 7/16" top thread on studs vs. the 3/8" on the LT1.




# HEAD GASKETS


The LT4 also features new composite head gaskets necessitated by higher compression ratio. Rather than the "impregnated surface" of the LT1's gaskets, the LT4's are "graphoil" with stainless steel fire rings.


# REVISED PISTON DESIGN


A gain in compression ratio, from 10.4:1 to 10.8:1, comes from machining the valve pockets in the pistons shallower than the LT1's.


# POSITIVE-TWIST TOP PISTON RINGS


A new top compression ring. High-speed durability tests of the engine revealed that ring flutter became a serious problem above 5,500 rpm, and the result was excessive blow-by. To cure this, something called a positive twist compression ring was specified. A chamfer cut into this type of ring's inside edge causes it to flex down in response to the introduction of cylinder gas pressure, leading to better sealing at higher rpm. "If you look closely at the inside edge of the ring, you can see that there's a chamfer cut on it, and by changing the cross-sectional area on that inside-and the properties associated with it was the end gap of the ring comes together, the ring actually takes on a slight positive twist. It is no longer perpendicular to the bore." But when cylinder gas pressure is introduced, the ring flexes down and seals better against the bore. "If you start with a ring that's flat, when you flex, you end up with a line seal, This way you end up sealing across a broader area."


# FUEL SYSTEM


The engine's higher rpm also exceeded the LT1's fuel injector's ability to keep up, so the LT4 got larger fuel injectors rated at 3.5 grams per second (28lbs/hr), replacing the 3.0 gram (24lbs/hr) injectors of the LT1. The larger injectors were designed to keep pace with the better breathing, higher revving engine.

The 48mm throttle body remained unchanged from the LT1, however all LT4 equipped Corvettes (not just Z16 Grand Sports) featured a throttle body top cover plate with the words "Grand Sport" in red letters.



# INTAKE MANIFOLD


A specific intake manifold was cast for use with LT4 heads. Although the manifold and head intake ports do not precisely match, the manifold was cast with additional material to allow safe machining of the ports to more closely match the LT4's higher head ports. LT4 intakes were powder coated red to differentiate them from the standard LT1 manifold.




# ROLLER TIMING CHAIN


Stock LT1 has powdered metal butt link chain drive for the camshaft and water Pump. LT4 has smaller but stronger steel roller chain. Although it seems that the new chain and sprockets would reduce mass, The cam sprocket was left solid, rather than webbed, specifically for additional mass. Increased inertia in the system reduces the tendency for cam torsion.



# SPECIALLY MACHINED CRANKSHAFT


The crank itself was improved via something called undercutting and rolling. Undercutting is the machining of a groove into the corner of a journal. Though this would seem to weaken the crank at that point, it actually makes it stronger where tensile stress is most likely to cause sudden failure. Rolling the undercut introduces compressive stress to the area. This makes it more durable, because potentially catastrophic tensile stress generated during high RPM operation must first overcome the compressive stress before that area of the crank is subjected to tension. Undercutting, a groove cut into the corner of a journal, looks counterintuitive, but makes a crankshaft stronger where tensile stress is most likely to cause failure. By undercutting and then rolling it, compressive stress is introduced. Tensile stress during high-speed operation first has to overcome the compressive stress before there's any tension on the joint. And as tensile stress is what breaks crankshafts, undercutting and rolling make the crankshaft stronger.


# DUAL-MASS FRONT TORSIONAL DAMPER


Tuned for high engine speed, also helps reduce stress on the crankshaft. LT1 pt.# 10128489 and LT4 pt.# 12551486


# NODULAR IRON MAIN BEARING CAPS


These LT4 components are considerably stronger than their LT1 counterparts and resist failure at higher RPM's.


# TEFLON REAR CRANK SEAL


Offers improved durability over the standard LT1 crank seal.


References:

* GM Assembly Manual (LT4)
* Chevy High Performance magazine March '99
* Chevy High Performance magazine October '95
* Vette magazine October '95
* Corvette Fever magazine November '95
* Corvette Fever magazine October '96
* Corvette Fever magazine March '99

The information presented here is believed to be accurate but the authors and the Grand Sport Registry assume no responsibility for errors. If you have evidence to the contrary on any of the above, or have worthwhile additions to increase the value of this information, please submit to info@grandsportregistry.com.

Many thanks to "Steve" as the original compiler of much of the above information.


LT1 vs. LT4

 

I kind of agree with this statement it does look out of place, but I also have thought about the possibility that this little oddity can make the L98 cooling much more efficient. I believe you could eliminate the hotspots at the back of the cylinder head by removing coolant from the rear of the manifold. Just my $0.02. John may want to add to this if he is reading this post.

 

iv seen that, there's still isn't much difference between the two intakes, and that's what were talking about right? every one knows that the extra 30hp was from the 1.6 rollers and the different cast heads with a Valve Diameter "2.00/1.55" and intake when looking at it from a far, since it seems you want to compare the lt1 vettes to the lt4 vettes, the lt1 engine is 785.3 lbs (356.2 kg) the lt4 engine is 1003.5 lbs (455.2 kg) in the 1/4
the lt4 was not much faster then the lt1 vette almost identical in comparison to the lt4 because the power band was moved up it only got the lt1 tords the end or right in the middle of the runs,
runnig a 10th or more faster (but i could be wrong), i dont want to start a flame war or anything,
but back to the the topic

 

Reason why the LT-4 intake is better:


Think of an LS-1 head's intake port. It's TALLER.

With that said, now look at a vortec/fast-burn/LT-4 head (intake ports) compared to a standard 23* head. The vortec/LT-4 intake port is taller than the standard chevy head intake port. The LS-1 intake port is even taller than the LT-4.

So why did the intake ports over the years get taller and taller over the previous years' designs?

Answer: better air velocity.

The LT-4 intake matches the taller port design of the head it was made for.

The LT-4 intake can also be converted to use with vortec/fast-burn heads. (Much like the LT-1 intake conversion for standard old-school small block heads).

On a side note: the vortec and fast-burn heads were cast very close to the LT-4 casting in port design.

Just food for thought!

 

you can port the lt1 intake a decent amount,

 

Damn. Didnt realize there was more weight period. Not to mention that much.

I would prolly choose the Mini-Ram just because it is "after-market". Woooooo


NeedForSpeed

Its all about everyones opinions. No flaming

 

Would there be any problem with removing the material between the two throttle bores on the LT1 like the MiniRam?

Same question for a TPI Plenum?

Not any gains q's but would it hurt?

 

You mean like the first pic how the ram has no pacific holes drilled to match the TB? if thats the case, what about the cut outs behide the TB for vaccum?

 

also specking of anyone seen this?

 

Here's a thought...

Could a head company machine/cast the intake side of the head to match the LT1/4 intake and the piston side to match a normal SBC setup? That would mean no force fitting the intake to theheads, right?

Jason

 

Was that question or an answer?

 

question

 

I think the biggest differences between the two intakes is the Miniram has an "air gap" between the bottom of the intake and the plenum, while the LT1 intake is a solid one piece unit AND the Miniram can be had with different sized intake ports (upto a Felpro 1206).

I have to agree with Vader and say the 1/2" runner length won't make much of a difference in TQ charateristics. The Miniram has a fairly flat TQ line as does the LT1.

I am a Miniram owner, and IMO, the best reason to get a Miniram is because you need the big port version. Everything else is just "cosmetics" but a much lower price.

 

I think TPiS did a good job on the fuel rail mounting boss's. there is a big difference in the lt1 mounting boss's(inside) and the MR boss's(inside.

 

Here is a Photo of my vortec lt4 with remote thermostat located under the throttle body. The fuel rail covers will cover most of the plumbing.

 

are you useing a vortec block, with LT4 parts?

 

I am using a 96 4 bolt truck block and heads. The heads have been modified for bigger springs and higher lift for the hotcam. The stock top radiator hose should fit on the remote thermostat housing if I cut a couple of inches off. I cut the corners off a stock vortec manifold and had them welded onto the lt4 manifold. I built a jig to line everything up and bolted the pieces on. Took it all to Jerry Long at Longs Machine in San Antonio and had it welded up and milled flat again. The welds look so good I didn't even grind them flat, just painted over them.

 

looks good, you going to dyno it soon time?

 

iv never seen a TB on a TPI setup like that

 

Looks like a nice, clean job, Larry. Where did we find the distributor hole?

 

For the distrubuter hole I bolted the old manifold onto my alignment jig and used a 1 3/8 hole saw for alignment to find the center. I welded a piece of 2 inch square tubing under it and drilled a 1/4 inch hole in the center. After I bolted on the lt4 manifold I used that to drill the pilot hole from the bottom side then used the hole saw to finish. Made a spacer like John Millican used on lt1 intake.com . Lined up great.

 

got any rear shot of the engine?

 

bump

 

bump, where did ya go, im intrested to see the rear on your intake

 

Here it is

 

wow that was a great idea..I am off to get me a lt1 intake right now.I work at a macine shop so all the fab work wont be a problem...once again great idea man..

 

Anyone thought about using an electric water pump, with temp sensor in the head to turn the pump on and off and just not using the external thermostat with the LT1 intake? In National Dragster, a company sells a controller switches back and forth between the cooling fan and the water pump. Tic-Toc or somthing like that.
With the electric water pump you can cool the engine between rounds and turn it off for the blast down the strip for max power.

 

Its from TPIS, called the "monoblade" flows 1300cfm, costs a buttload, and according to there ads "you will have to convince them that you need it "

 

The throttle body is stock with blue masking tape to keep the dust out. If i forget to take it off it might not run too good!

 

I think he's talking about the monoblade one a few posts above your completed engine.

-- Joe

 

can someone explain the whole remote thermostat thing....

 

we could... but on 2nd thought... naaaw..

just go to LT1intake.com




oh ok fine...

the LT1 does not have a thermostat housing on the intake like the Gen I intakes.. also the LT1 intake does not have any coolant running in it, or coolant passages as most call it.. so... the problem is, how do you get the water out of the heads and back into the radiator?
well you have to drill holes in the LT1 intake where the water outlets are on the Gen I heads.. well you still need a thermostat to control the water temp.. so.. you route the 2 new coolant lines, to the remote thermo, and then the thermo sends that water back to the radiator..

if you even ask, "why cant i just send the water straight to the radiator instead of this remote thermo".. im going to hurt you..

thats just the same as take out your thermo in your current TPI.. problem with that is, the water is then running into the radiator too fast.. and can have adverse affects on cooling..

what are they you ask? on a cold day, if you have no thermo, the water will always be cold and your computer will always run open loop, rich. it will try and bring up the RPMs to heat up the engine to normal operating temp.. not good.

 

i know all about open and closed loop and thermostats

thx for explaining about the intake, thats what i didnt get

 

I am still waiting for someone with a welder to make coolant flow under and through the front of the lt1 intake make a box on the inside and machine the front edge under the throttle body so you could use a thermostate housing like a 2.3 quad 4 uses. would be just as clean as the miniram at litterally a fraction of the cost

of course to make this worth while you would have to weld it yourself


whould be even better yet to run the egr too!

how ever I really have been waiting for the coolant one. If I had the spoolgun for my miller I would have done this the the intake I have

 

Old thread back from the dead. I have been working on this for a while on and off and finally made some progress on my ideas.

Installing the entire back section of a TBI intake onto the LT1 intake so it incorporates the water crossover and stronger dead on distributor mount & location.

Adding the front mount bolt & water passage areas from the donor TBI intake as well.

Just got the TBI intake blasted & cut apart and got the LT1 intake cleaned up and blasted too. Now I just need to get a new bottle of argon for my TIG so I can get the real work moving forward.

 

I was just going to put the hose fittings for the remote thermostat into the front like the other swaps have done but after reading the previous post I am going to work on getting some Quad-4 donor parts to see what I can make fit.

At the least I will put the internal water crossover into the front of the intake.

 

wow, i was wondering the exact same thing! looks like you have a good start.

 

I do it on most even the L98
Hurt no gain whose to say.

There is a sizeable difference between the mini and the LT1.

Take a good look inside the plenum and youll have your answer the mini can support more power period.

Do you NEED the mini ? Depends on what youre building.

That is one intake Id almost consider getting a dual lobe design to the issues of charges getting robbed from one another. Maybe. Splitting hairs at that point